TABLE OF CONTENTS
Introduction. . .
Variety Development .
Culture and Fertility .
Weed Control. . .
Disease . . .
Water . .. .
Nematodes . ..
List of Contributing Faculty.
1Professor (Plant Pathologist), Professor (Soil Scientist), Assistant
Professor (Plant Breeder), respectively.
AGRICULTURAL RESEARCH AND EDUCATION CENTER
IFAS, University of Florida
13138 Lewis Gallagher Road
Dover, Florida 33527
Dover AREC Research Report DOV1987-5 November, 1987
ABSTRACTS OF PUBLICATIONS FROM AREC-DOVER FROM 1982 TO 1987
C. M. Howard, E. E. Albregts, and C. K. Chandler1
The primary goals of the Agricultural Research and Education Center, Dover are
to: (A) develop high yielding, disease and pest resistant strawberry varieties
adapted to Florida; (B) study the occurrence, distribution, severity, and control
of diseases of strawberries and vegetables (primarily strawberries); (C) develop
information on improved methods of fertilization and culture of strawberries;
(D) add to the worldwide body of scientific information in the above specific
areas of study; (E) cooperate with researchers in other disciplines to solve
problems on strawberries in Florida; and (F) serve as technical resource support
to County and State, agricultural extension staff.
Some of the accomplishments of the research programs at AREC-Dover during the
past 16 years that the programs have been in effect are: (A) correlation of leaf
number at transplanting to fruit yield response of 4 strawberry cultivars; (B)
demonstrated that strawberry plants receiving no chilling in the nursery require
adequate foliage to establish in the fruiting field and produce acceptable early
and total yields; (C) demonstrated that cycling of irrigation for strawberry plant
establishment and the use of a tail water recovery system can reduce water
consumption from the aquifer without any detrimental effect on strawberry plant
establishment and fruit production; (D) showed that strawberry plant stress before
or after transplanting can reduce early growth and fruit yields; (E) demonstrated
that storing strawberry plants in a cooler for longer than 2 to 3 weeks or
setting plants in late October or November will delay fruit production; (F)
demonstrated timing and the quantity of each plant nutrient taken up by the
strawberry plant; (G) demonstrated the proper placement of fertilizer in plant
beds and developed information on slow release fertilizers for strawberry; (H)
discovery of 2 new strawberry diseases; (I) discovery of a Benlate resistant strain
of powdery mildew on some northern grown strawberry transplants; (J) publication
of bulletin 841 "Strawberry Production In Florida" and bulletin 857 "Diseases,
Nematodes, Mites, and Insects Affecting Strawberries In Florida"; and (K) assisted
with the registration of one fungicide, one miticide, and one herbicide for use on
strawberries in Florida.
Abstracts of publications and presentations at scientific meetings by AREC-Dover
researchers during the six year period from 1982 to 1987 are presented below.
1. Albregts, E. E., and C. M. Howard. 1982. Strawberry variety trials 1980
and 1981. Dover AREC Research Report SV-1982-1. 6 pp.
Marketable fruit yields for the 'Dover' cultivar were high both seasons.
Breeding lines 77-163 and 77-169 had high yields the second season but
less than 'Dover' the first season. There was some root knot nematode
infestation in the two breeding lines the first season which may have
reduced yields. Total marketable yields of 'Tufts' were less than 'Dover'
both seasons and less than the two breeding lines the second season. For
the two seasons, the January yield of 'Tufts' was less than the January
yields of 'Dover' and breeding lines 77-163 and 77-169. January yields for
'Pajaro' the second season were also fairly good. However, 'Dover' and the
two breeding lines produced a greater percentage of their fruit before
April than did all other cultivars.
2. Albregts, E. E., and C. M. Howard. 1982. Strawberry variety trials 1982.
Dover ARC Research Report DOV-1982-4. 6 pp.
January marketable fruit yields were highest for 'Dover' and breeding lines
77-163, 77-869, and 78-1268. The February yields of these same clones were
also among the highest. Early (December and January) fruit production is
important since fruit prices generally decline with time with the lowest
prices coming in April. 'Tufts', 'Douglas', and 'Pajaro' yields for
January and February were among the lowest of all hatones tested. March
yields of 'Tufts', 'Douglas', and 'Pajaro' were among the highest.
3. Albregts, E. E., and C. M. Howard. 1983. Strawberry variety trials 1983.
Dover ARC Research Report DOV-1983-2. 9 pp.
January marketable fruit yields were highest for clones 80-456, 'Florida
Belle', 80-1283, 77-163, 80-1232, 80-733, and 80-933. Clones 77-163, 80-733,
80-933, and 80-1283 also gave high February yields. 'Douglas', 'Tufts',
'Pajaro', 77-869, and 80-1340 yields were low in January and February.
Since fruit prices generally decline with time, early yields (December and
January) are important for a profitable season.
Seasonal marketable yields were numerically highest with the clones 80-456,
80-1232, 80-933, 80-733, 80-991, 77-198, 77-873, and 80-1283. Seasonal
yields were numerically lowest with 'Douglas', and 'Tufts'. 'Douglas' had
the lowest percentage of its fruit rated cull while clones 80-1283, 'Dover',
80-852, and 77-873 had the greatest percent cull fruit. As noted in Table 2
most cull fruit are harvested late in the season. The principal reason for
cull fruit is small size. The large number of fruit on some clones during
the latter part of the season plus the high temperatures often encountered
at that time result in many small fruit. This is especially true of those
fruit ripening last in a fruiting cycle.
4. Albregts, E. E., and C. M. Howard. 1984. Strawberry variety trials 1984.
Dover ARC Research Report DOV-1984-3. 9 pp.
December marketable fruit yields were confined to the day-neutral cultivars,
'Fern' and 'Selva', and to three of the breeding lines. February yields were
highest with clones 81-318, 81-2689, 80-866, 81-2553, and 'Dover'. Lowest
February yields were from clones 79-1125, 'Selva', 'Fern', and 'Santana'.
Seasonal yields above 3000 flats/acre were harvested from clones 81-2465,
80-1340, 79-1126, 81-1183, 81-872, and 'Dover'. 'Tufts', and 'Pajaro' gave
high seasonal yields, but yields came late in the season when fruit prices
were very low.
Average marketable fruit weight was highest with 'Santana' followed by
81-2689, 'Parker', 80-866, and 79-1126. All cultivars, except 'Dover', 'Fern',
and 'Selva' plus breeding lines 81-2465 and 79-1126 had low percentages of
their fruit rated as cull. Cull fruit were generally the result of small
fruit harvested late in the season when large numbers of fruit are on the
plant at one time.
5. Albregts, E. E., and C. M. Howard. 1986. Strawberry variety trials 1986.
Dover AREC Research Report DOV-1986-1. 11 pp.
Only 'Selva', a day neutral cultivar, produced fruit in December; the yield,
45 flats per acre, was added to the January yields. Clone 81-2689 gave
highest January yield. Clones 81-1350, 82-1452, 82-576, 82-594, 'Chandler',
and 'Selva' also produced high January yields.
Since 'Chandler' and 'Selva' were grown in Canada and removed late from the
nursery, flower initiation had occurred in the nursery. Since plants from
Florida nurseries generally initiate flower later than those grown in Canada,
the Canadian grown plants would be expected to have high early yields.
February yields of 'Chandler' and 'Selva' were reduced while those clones
producing high January yields also produced high February yields. Fourteen
clones, but no cultivars, produced yields greater than 2500 flats/acre.
Highest seasonal yields were produced by clones 82-576 and 81-2689. Highest
average marketable fruit weight for total yields were from clones 82-594,
81-2689, 82-1452, and 'Pajaro', all exceeded 17 g. The percent cull yields
were lowest with 'Selva', Ten other clones had percent cull yields of less
than 20%. If the average cull fruit weight was less than 7 g, over 50% of the
culls were small fruit. If fruit weight was greater than 7 g, greater than
50% of the culls were the result of rots. Culls from clones 'Pajaro' and 82-
594 were mostly from rots.
6. Albregts, E. E., and C. M. Howard. 1987. Strawberry variety trials 1987.
Dover AREC Research Report DOV-1987-2. 8 pp.
Several clones produced fruit in December. 'Douglas' had received chilling
in the nursery prior to setting in fruiting plots, and 'Selva' is a day
neutral cultivar. Neither 'Douglas' nor 'Selva' produced well in January or
for the season. Florida breeding lines 81-2689 and 81-1350 produced some fruit
in December and the highest yields in January. Highest seasonal marketable
yields were produced by FL-84-1528, FL-81-2465, FL-84-2260, FL-79-1126, and
FL-83-457. Seasonal yields were very low with the 3 cultivars. 'Selva' was
infested with mites upon planting and plants were never completely free of
them which probably reduced 'Selva' yields. However, 'Douglas' plants were
some of the largest in the trial while 'Pajaro' were of normal size, yet both
produced poor yields. Highest average marketable fruit weight came from
FL-82-594 and FL-82-1452. Seven other Florida breeding lines produced fruit
averaging 16 g or more. Clones producing more than 75% of their fruit as
marketable were FL-82-1452, FL-83-418, and FL-83-3385. Forty-three percent of
the 'Douglas' and 'Pajaro' fruit were cull; about one-half were too small and
one-half had rots. Breeding lines FL-82-67 and MS-74 had lowest percent
marketable fruit and these were noted cull mostly because of small size.
CULTURE AND FERTILITY:.
7. Albregts, E. E., and C. M. Howard. 1982. Effect of transplant stress on
strawberry performance. HortScience 17 (4):651-652.
Subjecting harvested transplants of strawberry (Fragaria X ananassa Duch. cvs.
Florida Belle and Dover) to excessive wilting increased foliage loss and
plant mortality and reduced plant size and January fruit yields.
8. Albregts, E. E., and C. M. Howard. 1982. Response of fruiting strawberries
to micronutrient fertilization. Proc. Soil and Crops Sci. Soc. Fla. 41:158-16C.
Strawberries (Fragaria X ananassa Duch.) were grown for two fruiting seasons
on a well drained fine sand which had not been fertilized for at least 12
years. Each season micronutrients were applied pre-plant as 1) fritted trace
elements (FTE 503) at 45 kg/ha, 2) as a mixture of micronutrients in the oxide
form applied at the rate of 680 g B and Cu, 4050 g Fe, 1690 g Mn, and 1580 g/
Zn/ha, 3) the oxide form of micronutrient applied at double the proceeding
rate, and 4) a control. There were no significant differences in fruit yields,
fruit quality, and elemental composition of the fruit because of treatment.
Treatment differences were obtained for Mn, Cu, and Zn content of the leaf
blades and the Zn content of the soil. The B content of the leaf blades was
in the deficient range with all treatments the second season, but no foliage
or fruit deficiency symptoms were evident.
9. Albregts, E. E., and C. M. Howard. 1982. Effect of fertilizer rate on number
of malformed strawberry fruit. Proc. Fla. State Hort. Soc. 95:323-324.
'Dover' and 'Tufts' strawberry (Fragaria X ananassa Duch.) plants were
fertilized at 65, 130, and 195 1bs/N/acre with isobutylidene diurea and
evaluated for number of malformed fruit of marketable weight. Phosphorus and
potassium were supplied to all treatments at 27 and 162 lbs/acre,
respectively. The percent of the fruit malformed increased with increased
nitrogen rate. The effect was most noticeable in the March and April
harvests. A greater percentage of the 'Tufts' than of the 'Dover' fruit were
malformed. Leaf N and soil NO3-N increased with increasing rates of applied N.
Foliage color was darker green and plant size was larger with higher rates
of applied N.
10. Albregts, E. E., and C. M. Howard. 1982. Effect of stress on strawberry
transplant growth and fruiting response. Dover ARC Research Report DOV-1982-
3. 5 pp.
Since most strawberry transplants set in the fruiting field in Florida are
not dormant, they are more subject to stress. Transplants are removed from the
soil in the nursery, placed in small bundles, and handled in various ways
until set in the fruiting field. Some transplants are set in the fruiting
field immediately after removal from soil, while others are placed in coolers
for an indefinite period before transplanting. Occasionally, growers will bur,
the plant roots in the nursery soil for periods ranging from one to five
hours. Some plants are occasionally left on the soil surface, either in the
nursery or fruiting field, for lengthy periods. Transplants are also placed
under stress between time of running the blade under the plants in nursery
until irrigation is started on transplants after setting in the fruiting
field. Because the weather is very warm during plant harvest, excessive
wilting of plants can occur with some harvesting, storing, and setting
procedures. If defoliation of non-dormant plants occurs, plant growth,
development, and fruiting may be delayed.
11. Albregts, E. E., and C. M. Howard. 1984. Effect of three slow release
fertilizers on fruiting strawberries. Proc. Soil and Crops Sci. Soc. Fla.
Slow release N fertilizers are included as part of the fertilizer mix to
reduce N leaching during the production of fruiting strawberries (Fragaria
X ananassa Duch.). Sludge (heat dried sewage sludge), ureaformaldehyde, a 1:1
mixture of sludge and urea-formaldehyde, and organiform were evaluated for
fruiting strawberries as the only source of N. Two rates of N (146 and 219
kg/ha) were applied. Treatments in which the nitrogen was derived from sludge
produced highest March, April, and total fruit yields, highest N03-N and
NH4-N in the soil solution, and highest total N in leaf tissue during
December. In addition these plants were larger and foliage greener in January
and February. Total fruit yields were higher with the highest N rate.
12. Albregts, E. E., and C. M. Howard. 1984. Boron application to strawberries.
Proc. Soil and Crops Sci. Soc. Fla. 43:11-14.
Experiments were conducted for two seasons, 1980-81 and 1981-82, using the
annual hill culture system for strawberries (Fragaria X ananassa Duch.) on
a well-drained Scranton adjunct fine sand (a siliceous, acid thermic, Typic
Psammaquent) at the Agricultural Research & Education Center, Dover, Florida.
During the first season, treatments were solubor applied to the foliage in
five monthly applications of 112 g B ha-1 each, borax incorporated into the
plant bed at 1.12 kg B ha-1, dolomite incorporated into the plant bed at
2.24 Mg ha" and an untreated check. During the second season two additional
foliar application rates were used, 56 and 224 g B ha"1 per application. The
'Dover' cultivar was used the first season and the 'Dover' and 'Tufts'
cultivars were planted the second season. Foliage application at 112 g B ha-
monthly gave the highest total marketable fruit yields during both seasons.
Dolomite application reduced the fruit yield the first season, but not the
Yields were more highly correlated with fruit number than with fruit weight.
The dolomite and the check treatments increased the percent malformed fruit
during both seasons. Soil application of boron resulted in the highest
concentration of B in the foliage and in the soil saturated extract.
13. Albregts, E. E., and C. M. Howard. 1984. Strawberry production in Florida.
Univ. of Fla. Expt. Sta. Bull. No. 841. 26 pp.
A review of the production and cultural practices for strawberries grown
in Florida. Information on site selection, bed preparation, plant source and
quality, planting date, weed control, fertilization, cold protection, and
harvesting and marketing of fruit are some of the practices discussed.
Nursery production and culture are also reviewed.
14. Albregts, E. E., and C. M. Howard. 1985. Short-term cold storage and soil
fertility during plant and fruit production on growth and fruiting of
strawberry. HortScience 20(3):411-413.
Strawberry plants (Fragaria X ananassa Duch. 'Dover' and 'Florida Belle')
produced increased December fruit yields during 2 seasons when stored at
20C for 1 week prior to transplanting rather than transplanting directly from
the nursery. The total fruit yield of 'Dover' decreased with storage the 2nd
season, whereas the total fruit yield of 'Florida Belle' was inaffected by
storage. Lowering the soil fertility in the nursery prior to plant harvest
increased 'Dover' December fruit yield the 2nd season, and increased
'Florida Belle' December yield both seasons. Total fruit yields of both
cultivars as related to nursery fertility were inconsistent. Total fruit
yields of 'Dover' in both seasons were greater with a fertilizer application
in the fruit production field of 224N-50P-224K kg/ha-1 than with double this
application. Total fruit yield of 'Florida Belle' was not affected by
fertilization in a fruiting field. During the first season, both cultivars
produced more misshapen fruit with the 448N-100P-448K kg/ha-1 application
than with the 224N-50P-224K kg/ha-1 application.
15. Albregts, E. E., and C. M. Howard. 1985. Correlation of leaf number at
transplanting to strawberry fruit yield. HortScience 20(3):415-416.
Optimum leaf number at transplanting, as related to fruit yield for
strawberry (Fragaria X ananassa Duch.) plants which had received no chilling
in the nursery, varied with cultivar. Leaf number optimum for 'Dover',
'Florida Belle', breeding line 77-163, and 'Pajaro' were 4, 4, 3, and
greater than 5, respectively.
16. Albregts, E. E., and C. M. Howard. 1985. Double cropping strawberries with
vegetables. Proc. Fla. State Hort. Soc. 98:299-301.
Sweet corn, squash, cucumber, and snap bean were double cropped on strawberry
beds immediately after fruit harvest ceased. Paraquat was applied to beds to
destroy all vegetation prior to planting the second crop each season. In 1981,
mulch remained on beds and fertilizer was applied at either 0, 30-13-25, or
60-26-50 lb./acre N-P-K. In 1982, polyethylene mulch was removed from one-half
of the plots. Sweet corn was fertilized at 60-24-50 or 120-48-100 Ib/acre
N-P-K whereas cucumber, squash, and snap beans received 30-12-25 Ib/acre
N-P-K. In 1983, all mulch was removed from beds, and crops were seeded at
2 densities. Sweet corn was fertilized at 50-24-48 or 100-48-96 lb./acre
N-P-K; cucumber and squash received 25-12-24 or 50-24-48 Ib./acre N-P-K. The
initial levels of soluble salts at saturation in ppm were 550 in 1983, 3300
in 1982, and 1700 in 1981 except with cucumber beds which had 2400. Yields
increased linearly with fertilizer rates with all crops except cucumber in
1981. Fertilizer rates in 1982 did not affect yields, (probably as a result
of the high fertilizer carryover) but squash yields increased with use of
mulch, Only cucumber yields were affected by treatments in 1983, when the
2x '? ilizer rate and the 12-inch plant spacing gave highest yields. All
cro-p yields were in the range of state averages. Soil soluble salt
concentrations were generally positively correlated with fertilizer rates
only early in the season. In 1982, beds covered with mulch maintained higher
levels of soil soluble salts all season than the unmulched beds.
17. Albregts, E. E., and C. M. Howard. 1985. Strawberry transplant quality for
the fruit production field. Dover AREC Research Report DOV-1985-2. 4 pp.
The quality of the strawberry transplant determines to a large extent its
fruiting capability. Quality factors which are normally visible include the
amount of foliage and its color, foliage diseases, root volume and color, and
crown size. Hidden quality factors are amount of nursery chilling, length of
storage in a cooler, and internal disease infections. Quality factors which
may or may not be noticeable are nematode and mite infections, pesticide
damage, excessive wilting or stress from time of digging to plant
establishment, and plants which have gone through a 'heat' in transit and/or
in storage. All of these factors can reduce plant growth and fruit yield.
18. Albregts, E. E., and C. M. Howard. 1986. Effect of runner removal on
strawberry fruiting response. HortScience 21(1):97-98.
Using the annual hill cultural system, runners of 2 strawberry cultivars were
removed twice monthly, monthly, or left on the plants during each of 2 seasons,
An additional treatment was the transplanting of runners into the planting
slits of the original transplants followed by removal of the original
transplants when the runners became established. 'Tufts' produced 2 to 8 times
more runners than 'Dover', over a 2 to 3 month period instead of one month
as with 'Dover'. Early marketable yields of 'Tufts' were reduced each season
when runners remained attached to the fruiting plants, and the total
marketable yield was reduced for the 2nd season as well. Yields were reduced
because of fewer marketable-size fruit. 'Dover' yields were unaffected by
runner removal treatments. Early and total marketable fruit yields of the
runner plants of both cultivars were reduced each season compared to other
treatments. Early yields of 'Dover' were greater than those of 'Tufts'.
19. Albregts, E. E., and C. M. Howard. 1986. Response of strawberries to
soil and foliar fertilizer rates. HortScience 21(5):1140-1142.
A 3 x 3 factorial study of soil and foliar-applied N, P, and K fertilizer
was conducted on 'Dover' and 'Tufts' strawberries (Fragaria X ananassa
Duch.) using the annual hill cultural system. Rates of soil-applied
fertilizer were: a) 0, b) 112N-12P-93K, and c) 224N-24P-186K (kg/ha-1). Rates
of weekly foliar fertilizer applications were a) 0, b) 1.20N-0.54P-1.02K, and
c) 2.40N-1.08P-2.04K (kg/ha-1). Increasing rates of soil-applied fertilizer
increased fruit yields, fruit number, foliar N and K, plant size, and
foliage color. Rates of foliar N, P, and K had much less effect than soil-
applied fertilizer. The greatest plant response to foliar fertilization was
with inadequate rates of soil fertilizer. Foliage damage was evident with
foliar fertilization, and damage was greatest' with'-t'hethfiight-foii.r-'aS&te.
20. Albregts, E. E., and C. M. Howard. 1986. Supplemental foliar fertilization
of fruiting strawberries. Proc. Fla. State Hort. Soc. 99:329-331.
A foliar fertilization experiment was conducted on fruiting strawberries
(Fragaria X ananassa Duch.) at AREC-Dover during the 1983-84 season.
Fumigated and polyethylene-mulched beds were fertilized with 200N-16P-155K
lb./acre of dry fertilizer prior to mulch application. Locally grown-'Dover'
and 'Tufts' plants were set on 12 Oct. 1983. Foliar fertilizer was applied
from 15 Nov. 1983 through 10 Apr. 1984. The rate at each application
(1 x = 0.28M-0.09P-0.10K lb./acre) and frequency of application were:
(A) 1 x twice-weekly, (B) 2 x1 twice-weekly (C) 1 xl once-weekly, (D) 2 x,
once-weekly,. (E) 1 x once every 2 weeks, (F) 2 x1 once every 2 weeks, and
(G) no foliar fertilization (control). Only the treatment receiving the 2 x
rate applied twice weekly gave lower fruit yields throughout the season. For
'Dover', the control treatment gave the highest seasonal fruit yield but was
different only from the treatment receiving the 2 x rate applied twice
weekly. For 'Tufts', the treatment receiving the 1 x rate applied once
weekly gave the highest seasonal fruit yield but was different only from the
treatment receiving the 2 x rate applied twice weekly. Fruit size, firmness,
and resistance to abrasion were not affected by foliar treatments. The
percent of the marketable size fruit which were misshapen or fan-shaped or
had green shoulders were different because of foliar fertilizer treatments,
but differences were not consistent between cultivars. Data indicated that
foliar fertilization of strawberries adequately fertilized prior to mulching
was not beneficial for fruit production.
21. Durner, E. F., E. B. Poling, and E. E. Albregts. 1986. Early season yield
responses of selected strawberry cultivars to photoperiod and chilling in a
Florida winter production system. J. Amer. Soc. Hort. Sci. 111(6):53-56.
'Douglas', 'Tufts', and 'Pajaro' strawberry (Fragaria X ananassa Duch.)
plants were sampled for 3 consecutive years ( 1984), and 'Chandler'
plants were sampled for one year (1984) from September through October from
a North Carolina nursery. Plants were subjected to short days (12-hr
photoperiod) at day/night temperatures of 15.50/4.4C in 1982-1983 and to
short days (9-hr photoperiod) and long days (9-hr photoperiod with a 3-hr
night interruption) with or without chilling 15.50/4.40 (day/night) or
22.00/18.00 (day/night), respectively in 1984 for 0, 1, 6, or 12 days in
the NCSU phytotron. After treatment, plants were shipped to Florida for
planting in the winter planting system for evaluation of early season yield
1 Dec. 15 Jan.). Optimum digging dates for all cultivars were observed to
be a photoperiod response. Chilling enhanced early yield for 'Douglas' and
'Pajaro' when plants were dug prior to or at the optimum date. Plants dug
later than the optimum date had much lower yields even with substantial
chilling. In 'Chandler', slight chilling ( 125 hr from 1 Sept. until
digging date) suppressed early yield, while increased chilling ( 125 hr)
enhanced early yield when plants were dug at or prior to the optimum date.
Chilling decreased early yield in 'Tufts' regardless of digging date.
Significant yield increases were only obtained with chilling much greater
than that which naturally occurs in North Carolina.
22. Albregts, E. E., and C. M. Howard. 1983. Weed control in the strawberry
fruit production field. Proc. Fla. State Hort. Soc. 96:75-76.
Herbicides were applied for 2 seasons to a strawberry (Fragaria X ananassa
Duch.) fruit production field. During the first season, herbicides were
applied on 3 October, 1980 in the row middles immediately after transplanting.
Treatments were napropamide (2-(a-naphthoxyl)-N,N-diethypropionamide) at 6 lb
a.i./acre, DCPA (dimethyl tetrachloroterephthalate) at 12 Ib. a.i./acre,
chloroxuron (3-(p-(chlorophenoxy)phenyl)-l,l-dimethylurea) at 6 Ib/a.i./acre,
and an unhoed check. Plots were evaluated and then cultivated on November 10,
December 4, and March 3. During the second season, herbicides were applied
on October 6, 1981 prior to transplanting to row middles and to beds with
mulch temporarily removed, and on December 28 to row middles only.
Treatments were DCPA at 9 lb. a.i/acre, paraquat (l,l'-dimethyl-4,4-
bipyridinium dichloride) at 1 lb. a.i./acre, napropamide at 2 and 4 lb. a.
acre, terbacil (3-tert-butyl-5-chloro-6-methyluracil) at 1/8 and 1/4 lb.
a.i./acre, and hoed and unhoed checks. During the first season, chloroxuron
and napropamide gave best weed control and smallest size weeds on November
10 and December 4 with no significant yield effects. During the second
season, napropamide and paraquat gave best weed control on December 1 and
December 28, and weed control was excellent in all herbicide treatments on
February 26. Herbicide drift in the paraquat treatment the second season
resulted in some plant damage which may have reduced yields. Evening primrose
(Oenothera laciniata, Hill) was the major weed both seasons.
23. Gilreath, J. P., and E. E. Albregts. 1984. Weed control in mulched straw-
berry production. Proc. Fla. State Hort. Soc. 97:171-174.
Preplant application of 1 and 2 Ib/acre of alachlor (2-chloro-2',6-diethyl-
N-(methoxymethyl)acetanilide) and 2 and 4 Ib/acre of ethofumesate
(2-ethoxy-2,3-dibydro-3,3-dimethyl-5-benzofuranyl methanesulfonate) and
postemergence applications of 0.5 lb/acre of two different brands of
acifluorfen (sodium5-(2-chloro-4-trifluoromety )-phenoxy)-2-nitrobenzoate)
were evaluated for weed control and crop phytotoxicity in mulched 'Tufts'
strawberries (Fragaria X ananassa Duch.) during the 1982-83 production
season. Alachlor and ethofumesate provided excellent early season grass and
broadleaf weed control. Acifluorfen (both brands) provided good control to
carolina geranium (Geranium carolinianum L.), but did not control grass
weeds. Strawberry plant vigor was reduced by the high rate of alachlor and
both brands of acifluorfen; however, the effect of acifluorfen was confined
to the foliage present at treatment and plants soon overcome the visible
injury. None of the treatments provided season-long weed control. Fewer
fruit were produced in herbicide treated plots than in the untreated
24. Gilreath, J. P., and E. E. Albregts. 1985. Weed control in the strawberry
summer nursery. Proc. Fla. State Hort. Sco. 98:258-263.
Herbicides and soil fumigants were evaluated for weed control and daughter
plant production in a strawberry (Fragaria X ananassa Duch.) summer nursery
in 1981, 1982, and 1984. In 1981, napropamide (2-(naphthoxy)-N,N-
diethylpropionamide) and DCPA (dimethyl tetrachloroterephthalate) were not
injurious to 'Dover' strawberry plants, while they severely reduced plant
vigor in 1982. Postemergence applications of acifluorfen (sodium 5- 2-chloro
-4-(trifluoromethyl)phenoxy -2-nitrobenzoate), fluazifop-butyl(butyl 2- 4-
5-(trifluoromethyl)-2-pyridinyl)oxy phenoxy propanoate) and sethoxydim
(2- 1-ethoxylmino )buty -5- 2-ethylthio propyll -3-hydroxy-2-cyclohexen-l-one)
did not reduce plant vigor in 1982, while application of bentazon (3-
isopropyl-lH-2,1l,3-benzothiadiazin-3(3H)-onee,e-dioxide) resulted in almost
Multi-chemical weed management systems were evaluated in 1984 with 'Dover'
and 'Florida Belle' strawberry plants. Two applications of napropamide and
alachlor (2-chloro-2',6'-diethyl-N-( methoxymethyl)acetanilide) reduced
strawberry plant vigor. After 3 applications of each preemergence herbicide,
1 application of fluazifop-butyl and 1 application of glyphpsate, (n-(
phosphonomethyl)glycine), plant vigor was reduced significantly. Four
application of napropamide, DCPA or alachlor, in conjunction with 2
applications of fluazifop-butyl and 3 wiper applications of glyphosate
controlled beggarweed (Desmodium tortuosum (Sw.) DC.) and goosegrass
(Eleusine indica (L.) Gaertn.) as well as hand wedbing..'.Acceptable cohtr6l--'
of hairy indigo (Indigofera hirsuta Harvery) was obtained with napropamide
+ fluazifop-butyl + glyphosate. Total number of 'Florida Belle' daughter
plants reduced by treatments containing napropamide and alachlor, while all
of the herbicide treatments reduced the number of 'Dover' plants produced.
25. Howard, C. M., and E. E. Albregts. 1982. Outbreak of Verticillium wilt of
strawberries in central Florida. Plant Disease. 66(9):856-857.
Verticillium wilt of strawberries (Fragaria X ananassa) was found in central
Florida for the first time in 1981. Surveys showed that all infected plants
came from two nursery fields in Michigan. The greatest percentage of wilt
occurred in plants that were grown in soil that had grown potatoes (Solanum
tuberosum) the previous year and was fumigated with 98% methyl bromide +
25 chloropicrin rather than 67% methyl bromide + 33% chloropicrin before
setting the strawberries. A formulation of 50% methyl bromide + 50%
chloropicrin at 420-470 kg/ha is recommended for control.
26. Howard, C. M., and E. E. Albregts. 1982. Strawberry anthracnose, crown rot,
and black leaf spot caused by Colletotribhum 'ftaiire. Dover'AREC-Research
Report DOV-1982-2. 5 pp.
Strawberry anthracnose, caused by the fungus Colletotrichum fragariae, Brooks,
has been a serious problem in summer plant production nurseries in Florida
at least since the late 1920's. The fungus is known to cause spotting and
girdling of runners and petioles, crown rot resulting in wilting and death of
plants, and fruit rot. Since the late 1970's, the anthracnose fungus has
been consistently associated with a black leaf spot of strawberry in the
summer nursery. Black leaf spot has now been shown to be caused by this
fungus and often is the first indication that the anthracnose disease is
27. Howard, C. M., and E. E. Albregts. 1982. Cleistothecia of Sphaerotheca
macularia on strawberry plants in Florida. Plant Disease. 66:261-262.
Cleistothecia of Sphaerotheca macularis were found in 1981 for the first
time on strawberry plants in Florida. They were found only on plants that had
been gpown in Maine and Michigan and were transplanted into Florida fruit
production fields. Benonyl and sulfur failed to control powdery mildew on
these plants. Powdery mildew was widespread on plants that had been grown
in five other states, but no cleistothecia were found on these plants, and
benonyl or sulfur controlled the disease.
28. Howard, C. M., and E. E. Albregts. 1982. Evaluation of fungicides for
control of strawberry fruit rots. Fungicide and Nematicide Tests. 37:50.
Strawberry plants were set through plastic mulch on raised beds on Oct. 9,
1980. Pesticides tested were Benlate, Topsin M, Captan, Rovral, Plictran,
Top-Cop S, and Difolatan. None of the treatments in this trial caused
phytotoxicity. Because of unusually cold weather the incidence of fruit rots
was very low. Only Alternaria fruit rot was sufficiently severe to analyze
statistically. No treatment significantly increased marketable fruit yield
above that in the check. Marketable yield was significantly less than the
check in plots receiving Top Cop S or Difolatan.
29. Howard, C. M., and E. E. Albregts. 1983. Black leaf spot phase of
strawberry anthracnose caused by Colletotrichum gloeosporioides (=C.
fragariae). Plant Disease. 67:1144-1146.-
Since the mid-1970's, a new leaf spot of strawberries has been found in
summer nurseries in Florida. Isolations from the lesions consistently yielded
a Colletotrichum sp. identical to the original description of C. fragariae.
In inoculation tests, an isolate from a leaf lesion and an isoat'e from the
crown of a wilted plant incited leaf spot and typical anthracnose symptoms
on stolons and petioles.
30. Howard, C. M., and E. E. Albregts. 1984. Anthracnose of strawberry fruit
caused by Glomerella cingulata in Florida. Plant Disease. 68:824-825.
Glomerella. cingulata was isolated from anthracnose lesions on strawberry
fruits. Lesions caused by G. cingulata on fruits in the field and
inoculated fruits were ind-stinguishable from those caused by Colletotrichum
fragriae. Conidia of G. cingulata were slightly shorter but larger in
diameter than those rertedffor C. fragariae.
31. Maas, J. L., and C. M. Howard. 1984. Variation of several anthracnose fungi
in virulence to strawberry and apple. Plant Disease. 69:164-166.
Isolates of Glomerella cingulata, Colletotrichum gloeosporioides, C.
fragariae, and dematu wereevaluated for vacation in pathogen ity
and virulence in-stra berry stolons and fruits and apple fruits. Isolates
of two nonstrawberry pathogens, C. trifolii and C. coccodes, were also
included as were subcultures of naturally occurrI g colony sectors of C.
gloeosporioides and G. cingulata from culture. Isolates of C. trifolii-were
virulent to moderately virulent in stolons. One isolate offT. coccodes and
several isolates of C. gloeosporioides and G. cingulata were as virulent as
C. fragariae in stolons.
32. Howard, C. M. 1984. Black leaf spot. p 52 In Compendium of Strawberry
Diseases, J. L. Maas, Editor. American Phytopath. Soc. St. Paul, Minn.
Black leaf spot is caused by Colletotrichum fragariae A. N. Brooks, the
same fungus that causes anthracnose of strawberry Lants( (see. Anthracnose
Fruit Rots; Anthracnose). In Florida, black leaf spot occurs only in the
summer nursery and in late April and May in the winter nursery. The
initially minute black spots enlarge to 0.5-2mm in diameter (Fig. 71).
Although many spots may be present on individual leaflets, they do not cause
death of the leaflets. The foliar disease usually appears only after
anthracnose has become moderate to severe on runners and petioles. At times,
however, black leaf spot appears first indicating that the anthracnose
fungus is present. At the first sign of black leaf spot, approved fungicides
should be applied according to label directions.
33. Howard, C. M. 1984. White rot. p 73. In Compendium of Strawberry Diseases,
J. L. Maas, Editor. American Phytopath. Soc. St. Paul, Minn. 138 pp.
White rot, reported in Florida, is caused by a fungus that has not yet been
identified but that may be a species of Rhizoctonia. Only ripe fruits
appear to be attacked, A large, soft, white or very light purplish area
appears on the red fruit. The entire fruit is invaded and becomes soft with-
in two or three days after infection is first evident (Plate 108). This
disease occurs erratically; it seems to appear suddenly in a particular
field, then disappears almost as suddenly.
34. Howard, C. M. 1984. Brown Cap. p 78. In Compendium of Strawberry Diseases,
J. L. Maas, Editor. American Phytopath. oc., St. Paul, Minn. 138 pp.
Brown cap is not a fruit rot, but it affects the marketability of strawberry
fruits. Caps that are killed by any agent become dry, shriveled, and
unattractive. Most of the organisms that cause leaf spots and many of those
that cause fruit rots can also cause brown cap. In addition to these
organisms, low humidity accompanied by wind can cause death of the caps and
subsequent development of brown cap (see also Leaf Scorch).
35. Howard, C. M. 1984. Anther and Pistil Blight. p 78. In Compendium of
Strawberry Diseases, J. L. Maas, Editor. American Phytopath. Soc., St. Paul,
Minn. 138 pp.
Anther and pistil blight occurs when Rhizoctonia fragariae Husain and McKeen
attacks unopened flower buds. This disease varies widely in severity. In
some flowers, some or all of the anthers are destroyed and appear dark
brown, but the pistils appear normal when the flowers open. Destruction of
the anthers results in destruction of the pollen in these flowers; however,
they can produce normal fruits after being fertilized by pollen from
healthy flowers. In more severe infections, some of the pistils are also
attacked. When these flowers first open, the anthers are dark brown and part
of the pistillate area of the flower appears smooth and devoid of pistils.
These flowers produce fruits with varying degrees of deformity, depending
on the number of pistils destroyed. In still other flowers, all anthers and
pistils are destroyed before the buds open; the entire centers of these
flowers are black, and they resemble flowers with freeze damage.
36. Howard, C. M., and E. E. Albregts. 1984. Anthracnose. In Compendium of
Strawberry Diseases, J. L. Maas, Editor. American PhytopaTh. Soc., St.
Paul, Minn. 138 pp.
Anthracnose diseases are caused by fungi that produce their asexual spores
in acervuli, including species of Gloeosporium and Colletotrichum. Several
species or biotypes of these fungi cause anthracnose of strawberry fruits
(see Anthracnose Fruit Rots), stolons, petioles, leaves (see Black Leaf
Spot), and crowns. The most serious anthracnose disease of strawberry kills
plants, causes fruit rot, and reduces runner plant production. This disease,
caused by C. fragariae A. N. Brooks, occurs in the southeastern United
Statesm frBi Florida and North Carolina to Louisiana, Oklahoma, and
Tennessee, and has been reported in Argentina, Brazil, India, Mexico, and
South Africa. It has been a serious problem in summer plant production
nurseries and fruit production fields in Florida and other southeastern
37. Howard, C. M., A. J. Overman, J. F. Price, and E. E. Albregts. 1986.
Diseases, Nematodes, Mites, and Insects affecting strawberries in Florida.
Univ. of Fla. Expt. Sta. Bull. No. 857. 41 pp.
Strawberry plants are grown in all months of the year in Florida in plant
nurseries during the winter, spring, summer, and early fall, and in fruit
production fields in the fall, winter, and spring. The warm, humid climate
of the state that permits year-round growth of plants in the field is also
ideal for the development of a large number of diseases and pests on the
crop as environmental conditions become favorable for their activity.
Growers must be concerned about growing disease-and pest-free plants that
will be used for fruit production or for establishing new nurseries.
This bulletin offers causes, symptoms, and control measures for strawberry
diseases and pests that are important in Florida. Since control
recommendations may change frequently, specific recommendations are not
listed. Consult extension or research personnel of publications for current
38. Howard, C. M., and E. E. Albregts. 1987. Evaluation of Fungicides for
control of anthracnose fruit rot of strawberry. Fungicide and Nematicide
Plants were set through black polyethylene mulch on raised beds on 23 Oct
1985. Fungicides tested were Difolatan, Captan, Thiram, Phaltan, Topsin-M,
Benlate, Rovral, and Ronilan. None of the treatments in this trial caused
visible phytotoxicity. Difolatan gave a significantly higher marketable
yield than any other treatment. Those treatments that gave higher weights
of marketable fruit also gave higher weights of ripe fruit with anthracnose.
There were only slight differences among the treatments in the percent of
ripe fruits with anthracnose and in average fruit size.
39. Mitchell, R. L., C. M. Howard, and E. E. Albregts. 1987. Evaluation of
fungicides for control of anthracnose fruit rot of strawberry. Fungicide
and Nematicide Tests 42:53.
This trial was established in a commercial field near Plant City, FL. on
7 Mar 1986 at the time the spring flush of fruit was emerging. Plants had
been set in double rows through black polyethylene mulch on raised beds in
Oct 1985. Fungicides tested were Captec, Bravo, Phaltan, Ridomil MZ,
Difolatan, Dyrene, Manzate, Thiram, Rovral, Cyprex, and Benlate. Captec and
Bravo treatments gave the highest weights of marketable fruit, although not
significantly higher than several other treatments. Captec and Bravo also
gave the lowest percentages of ripe fruit with anthracnose. Bravo caused a
mild to moderate foliage burn and Dyrene caused severe foliage burn. The
burn was noticed after eight applications but it is not known when it first
40. Howard, C. M., and E. E. Albregts. 1987. Evaluation of fungicides for
control of strawberry fruit rots. Fungicide and Nematicide Tests 42:54.
Plants were set through black polyethylene mulch on raised beds on 22 Oct
1984. Fungicides tested were Captan, Benlate, CGA-449, Drawifol, DPX-H
6573-65, and Tilt. Only the plots sprayed with Captan gave a significantly
higher marketable yield than the unsprayed check. Captan applied once or
twice per week was the only fungicide that significantly reduced anthracnose
CGA-449, Drawifol and Captan (applied twice/wk) significantly reduced gray
mold below that in the unsprayed check. None of the fungicides tested
caused detectable phytotoxicity.
41. Albregts, E. E., and C. M. Howard. 1985. Water use in strawberry transplant
establishment. Dover AREC Research Report DOV-1985-5. 4 pp.
Strawberry growers employ large amounts of overhead sprinkler irrigation
to establish transplants. Bare rooted strawberry transplants set in black
polyethylene mulched fruiting beds or in unmulched nursery beds are
established by overhead sprinkler irrigation operating for about 8 hours
daily for a period of 10 to 14 days. Intermittent irrigation can be
employed to give a considerable reduction in water use if the following
guidelines are met: 1) turn irrigation on as soon as plants are set; 2)
throughly moisten transplants and mulch during the time irrigation cycle
is on; 3) resume the irrigation "on" cycle before the plants become dry;
4) do not permit the plants to wilt excessively during the "off" cycle; and
5) during hot, dry, or windy weather "on" cycle must be longer and "off"
cycle must be shorter.
42. Albregts, E. E., and C. M. Howard. 1985. Effect of intermittent
irrigation on establishment of strawberry transplants. Soil and Crop Sci.
Soc. Fla. Proc. 44:197-199.
Diurnal intermittent sprinkler irrigation intervals (min on/min off) of
3/17, 5/85, 5/15, 10/20, 15/15, and continuous the first season, and 5/25,
5/15, 5/10, and continuous the second season were evaluated for establishing
strawberry (Fragaria X ananassa Duch.) transplants on black polyethylene
mulched beds. Leaf loss during the establishment period generally increased
with increased length of the 'off interval' and decreased length of the
'on interval'. Plant mortality was greater with the 3/17 and 5/25 treat-
ments. Seasonal yield was reduced the first season with the 5/25 treatment.
January yield was reduced with the 3/17 and 5/25 treatments. Leaf number
and plant mortality after establishment were the principal variables which
affected fruiting response.
43. Albregts, E. E., and C. M. Howard. 1986. 1985 Climatology report and
historical information from 1929-1985. Dover AREC Research Report DOV-1986-
2. 17 pp.
This report contains weather data for the Agricultural Research and
Education Center at Dover, Florida for the year 1985 and historical
information and averages for the years 1929 through 1985.
The present weather station is located 7 miles west of Plant City. Until
November of 1963, the weather station was located at Springhead, about
three miles southeast of Plant City. All precipitation measurements were
made at 8 a.m each day and represent the previous 24 hour period.
Temperature data is taken at 8 a.m. in a standard weather instrument
shelter approximately 4 feet above the ground and the data is the recorded
high and low for the previous 24 hours.
44. Albregts, E. E., and C. M. Howard. 1986. Cycling irrigation for freeze
protection during a radiation freeze. Soil and Crop Sci. Soc. Fla. Proc.
Thermocouples were attached to the surface of strawberry (Fragaria X
ananassa Duch.) flowers to monitor their temperatures during freezes.
Flowers and thermocouples were located above the foliage and exposed to
the sky. During radiation-type freezes, water was supplied by overhead
sprinkler irrigation for 15 min and then shut off until thermocouples
reached -1.1, -1.7, or -2.20C or for 15 or 30 min, whichever came first.
Air temperatures were monitored in weatherhouses located either 1.2 m
above the soil surface or on the ground, and also with unpainted and
exposed thermocouples located on black polyethylene non-irrigated beds.
Relative humidity was monitored in the 1.2 m weatherhouse. Foliage damage
occurred with the longer off-intervals and lower flower temperatures. The
bed thermometers gave the best correlation of air temperature with length
of time for flower surface to reach -l.l1C after irrigation was stopped.
The regression equation was: time in min = 17.07 + 3.24X1 + 0.08X2 where
X1 is the air temperature on the non-irrigated bed and X2 is the relative
humidity. The R2 was 0.76**. Damage to fruit and foliage was slightly
greater at lower flower temperatures and if the off interval was 30 rather
than 15 min. Cycling of irrigation during radiation type freezes seems to
be feasible when the temperature on the mulch is -3.90C or above.
45. Hochmuth, G. J., S. R. Kostewicz, S. J. Locascio, E. E. Albregts, C. M.
Howard, and C. D. Stanley. 1986. Freeze protection of strawberries with
floating row covers. Proc. Fla. State Hort. Soc. 99:307-311.
Three types of nonwoven and 3 types of polyethylene row covers were evaluat-
ed alone, and with drip or sprinkler irrigation for freeze protection of.
strawberries (Fragaria X ananassa Duch.) at Gainesville and Dover, Fla.
Treatments were applied only during freeze events. Thirteen freeze events
occurred at Gainesville during the 15 Dec., 1985 to 31 Jan., 1986 period
while only 4 freeze events occurred during the same period at Dover. Air
and flower temperatures were' higher under row covers compared to that in
the uncovered treatment. However, during the 25/25 Dec., 1985 freeze, only
the 1.5-oz polypropylene (Dover) and the 2.0-oz polypropylene and the
polyethylene blanket row covers (Gainesville) maintained temperatures above
300C. Early (Dec. and Jan.) fruit yield produced with some covers used alone
was equal to that obtained with sprinkler irrigation alone. At Gainesville,
the use of certain row covers in conjunction with sprinkler irrigation, but
not with drip, resulted in increased early yield over use of row cover or
sprinkler irrigation alone.
46. Zazueta, F. S., E. E. Albregts, and C. D. Stanley. 1986. Rainwater
harvesting and irrigation tailwater recovery to reduce water use for
fruiting strawberry. Soil.and Crop Sci. Soc. Fla. Proc. 45:129-131.
Rainfall and irrigation runoff were collected in a man-made retention pond
for a period of 1 yr and reused for strawberry (Fragaria X ananassa Duch.)
irrigation. The study was conducted at a commercial strawberry production
site without changing cultural and other practices. For the specific
condition of this site and for 1 yr, pumping from the aquifer was reduced
by more than 50%. The potential water savings resulting from harvesting
precipitation and recycling irrigation runoff were demonstrated.
47. Overman, A. J., and C. M. Howard. 1984. Influence of Nemacur and Vydate on
root-knot, sting, and stunt nematodes and strawberry yield, 1982. Fungicide
and Nematicide Tests, 39:98.
Soil treatments were applied on Oct 8; foliar sprays were initiated Dec 21
at first heavy bloom and applied weekly 3 times thereafter. Soil treatments
were incorporated 5 cm deep on the bed surface (0.6 m wide) prior to
sealing a full-bed film of 1.25 mil black polyethylene over each plot. The
nematode population in soil of each plot was estimated by a modified
Baermann technique prior to treatment, 11 weeks after soil treatment (at
the time of the first foliar spray), 15 weeks after soil treatment (1 week
after the 4th spray), 26 weeks after soil treatment (at the end of the
No treatment significantly influenced strawberry fruit yields. Both rates
of Nemacur controlled nematodes throughout the season. Vydate controlled
nematodes only after application of the 4 weekly foliar sprays but there
was no difference in nematode control between the two concentrations of
LIST OF CONTRIBUTING FACULTY, APPOINTMENT DATE, AND AREA OF SPECIALIZATION
FROM AREC-DOVER AND GCREC-BRADENTON IN 1986.
Albregts, E. E., 1967, Soils Chemist. Center administration, production, soil
and plant nutrition of strawberry and vegetable crops.
Howard, C. M., 1967, Plant Pathologist. Strawberry breeding and etiology and
control of strawberry and vegetable diseases.
Chandler, C. K., 1987, Assist. Plant Breeder. Strawberry breeding and genetics
of strawberry and vegetable crops.
Gulf Coast Research and Education Center Bradenton, Florida
Gilreath, J. P., 1981, Assoc. Horticulturist. Weed control of vegetable and
Overman, A. J., 1945, Nematologist. Etiology and control of nematode problems
on ornamentals and vegetables.
Price, J. F., 1978, Assoc. Entomologist. Identification, biology and control
of insects and mites of ornamental and strawberry crops.
Stanley, C. D., 1979, Assoc. Soil Scientist. Soil-water relations for ornamental
and vegetable crops.
The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
research may be found on the
Electronic Data Information Source
site maintained by the Florida
Cooperative Extension Service.
Copyright 2005, Board of Trustees, University