AGRICULTURAL RESEARCH CENTER
x' IFAS, University of Florida /
z- Dover, Florida / -
Dover ARC Research Report SV-1981-2 /Aug /B
ABSTRACTS OF PUBLICATIONS FROM ARC-DOVER FROM 1976 TO T8 19
C. M. Howard, E. E. Albregts and W. E. iatrs Up,
The primary goals of the Agricultural Research 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 and vegetables;
(D) add to the world-wide body of scientific information in the above specific
areas of study; (E) cooperate with researchers in other disciplines to solve
problems on strawberries and vegetables produced 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 ARC-Dover during the past
13 years that the programs have been in effect are: (A) development of the
strawberry varieties 'Florida Belle' and 'Dover'; (B) improvement in placement and
types of fertilizers used; (C) discovery of seven new diseases of strawberries and
one of snap beans; (D) assistance with registration of two new miticides ( through
cooperation with AREC-Bradenton entomologists) and three new fungicides for use on
strawberries in Florida; (E) development of methods whereby plants of California
strawberry varieties, most of which are highly susceptible to the devastating
anthracnose disease, could be produced successfully in Florida; and (F) development
of intermittent irrigation to establish strawberry transplants in the fall, thereby
decreasing water and energy usage and production costs.
Abstracts of publications and presentations at scientific meetings by ARC-Dover
researchers during the five year period from January 1976 to August 1981 are
ABSTRACTS OF PUBLICATIONS
1. Howard, C. M., and E. E. Albregts. 1979. Dover, a firm fruited strawberry
with resistance to anthracnose. Univ. of Fla. Expt. Sta. Circular S-267.
One of the major efforts in strawberry breeding in recent years in
Florida has been, and continues to be, development of cultivars with
resistance to anthracnose, caused by the fungus Colletotrichum fragariae
Brooks. Anthracnose is a devastating disease on highly susceptible
cultivars and often causes complete loss of strawberry nursery fields
when attempts are made to grow plants of these cultivars in Florida
during the summer. When plants of these cultivars are dug from nurseries
that appear to have a low incidence of disease, many of the plants often
wilt and die after transplanting. Up to 80 percent of the plants have
been lost in individual fruiting fields by late March. 'Tioga' and
'Tufts' are presently the favored cultivars in Central Florida, but
because of their high susceptibility to anthracnose, growers seldom
try to produce plants of these cultivars in Florida. The disease has
become well established on these cultivars in North Carolina, where
central Florida growers obtain the major portion of their transplants,
and has been the cause of majob economic losses to plant producers in
North Carolina and fruit growers in Florida. 'Dover' has shown excellent
resistance to anthracndoe in F1orida. It has generally outyielded all
other cultivats in cental Florida and has a firm fruit with excellent
2. Albregts, E. E., and C. M. Howard. 1976. Effects of antitranspirants on
strawberry plant response. Proc. Soil and Crop Sci. Soc. Fla. 35:67-69.
The foliage of strawberry (Fragaria x ananassa Duch.) transplants was
treated with antitranspirants to enhance early growth and survival in
the greenhouse. Folicote and Vapor Gard suppressed the transpiration
rate. However, plant condition at termination of greenhouse trials was
unsatisfactory with any antitranspirant treatment. The above anti-
transpirants were used in a field trial with continuous or 30 minute
intermittent overhead sprinkler irrigation, but neither plant condition
nor marketable yield were affected significantly by treatments. Inter-
mittent irrigation did appear to be a promising method to reduce water
consumption without affecting earliness of yield or seasonal yield.
3. Albregts, E. E., and C. M. Howard. 1976. Response of four okra cultivars
on mulched beds to plant density. HortScience 11:242.
Four cultivars of okra (Abelmoschus esculentus (L.) Moench) were grown
with densities of 22, 65, and 130 plants/square meter on polyethylene
mulched beds. Within cultivars, pod number and marketable yield per
unit were not affected by plant density, but pod number and marketable
yield/plant decreased with increasing density. Average pod weight with
3 of 4 cultivars was inversely related to plant density. Stalk diameter
decreased with increasing density, and plant stunting occurred at the
4. Howard, C. M., and E. E. Albregts. 1976. 'Florida Belle' Strawberry.
'Florida Belle' is a high yielding, large fruited strawberry (Fragaria x
ananassa Duch.) that has consistently shown good performance for the
fresh market in trials in central Florida.
5. Howard, C. M., K. E. Conway, and E. E. Albregts. 1977. A stem rot of bean
seedlings in Florida by a sterile fungus. Phytopathology 67:430-433.
A stem rot disease of bean seedlings, which first was observed in
central Florida in 1968, resembled southern blight which is caused by
Sclerotium rolfsii. However, lesions on infected stems never extended
above the soil line, and there were no sclerotia on the stems or on the
surface of surrounding soil. Isolations from the stems consistently
yielded a sterile fungus which failed to produce sclerotia after pro-
longed growth in culture or on infected plants. Pathogenicity of this
fungus was proved on beans grown in artificially infested soil. The
identity of the fungus was not determined because of the lack of
reproductive structures. Hyphal clamp connections indicate that it is a
Basidiomycete, and its cultural and other characteristics are similar to
those of Athelia spp. that have been classified on the basis of the
6. Albregts, E. E., and C. M. Howard. 1978. Elemental composition of fresh
strawberry fruit. J. Amer. Soc. Hort. Sci. 103:293-296.
Fruit and calyx of four strawberry clones (Fragaria x ananassa Duch.)
were analyzed for N, P, K, Ca, Mg, Fe, Zn, Mn, B, and Cu content for
2 seasons. The elemental concn varied because of the year, the clone,
and the time of season. The concn of the elements in the fruit decreased
in the following order: K, N, P, Ca, Mg, Fe, B, Mn, Zn, and Cu. The
elemental concn was greater in the calyx than in the fruit, probably as
a result of the much higher dry weight content of the calyx. The total
elemental content in kg/ha of the fruit and calyx for a season ranged as
follows: K from 40 to 67, N from 33 to 49, P from 6 to 9, Ca from 5.4 to
7.5, Mg from 3.7 to 5.7, Fe from 0.11 to 0.15, Mn from 0.05 to 0.10, B
from 0.04 to 0.09, Zn from 0.04 to 0.06, and Cu from 0.012 to 0.016.
7. Howard, C. M., and E. E. Albregts. 1980. 'Dover' Strawberry.
'Dover' is a high yielding, firm fruited strawberry (Fraqaria x ananassa
Duch.) with excellent resistance to anthracnose. It has consistently
shown good performance for the fresh market in trials in central Florida.
'Dover' is named for the village of Dover centered in the major strawberry
production area in west-central Florida.
8. Schuster, D. J., J. F. Price, C. M. Howard, and E. E. Albregts. 1979.
Twospotted spider mites: Control on strawberry with organotin, naphthoquinone,
and cyclopropane acaricides. J. Econ. Entomol. 72:360-361.
Efficacy of selected compounds from recently developed groups of
acaricides was evaluated in 3 winter field experiments for control of
Tetranychus urticae Koch on strawberry. The naphthoquinone, DPX-
3792(2-acetyloxy)-3-dodecyl-1,4-naphthalenedione), and the organotin
compounds, cyhexatin, hexakis, and R-28627 (S-tricyclohexyltin 0,0-
diisopropyl phosphorodithioate), effectively reduced mites and their eggs
below levels that developed on strawberry foliage treated with water
alone. Fruit yields from plants treated with these compounds were as high
as or higher than yields from plants to which no acaricides were applied.
The cyclopropane compound, ZR-856 (hexadecyl cyclopropanecarboxylate),
was effective against T. urticae but reduced yields in one experiment.
The carbamates, benom/y and oxamyl, were not as effective in reducing mite
populations as the aforementioned chemicals but did significantly reduce
populations relative to those on plants sprayed with water only.
9. Schuster, D. J., J. F. Price, F. G. Martin, C. M. Howard, and E. E. Albregts.
1979. Tolerance of strawberry cultivars to twospotted spider mites in
Florida. J. Econ. Entomol. 73:52-54.
Two experiments were conducted in Florida to determine the tolerance of
four strawberry cultivars to Tetranychus urticae Koch by comparing
populations of mites on plants treated or not treated with cyhexatin for
mite control. Based on percent reductions of both numbers and weight of
marketable fruit in the presence of dense mite populations, 'Florida Belle'
and 'Sequoia' were more tolerant to T. urticae than were 'Tioga' and
'Siletz.' Cyhexatin significantly reduced mite populations on all
cultivars. There were no significant differences among cultivars in
numbers of mites present.
10. Albregts, E. E., and C. M. Howard. 1980. Accumulation of nutrients by
strawberry plants and fruit grown in annual hill culture. J. Amer. Soc.
Hort. Sci. 105:386-388.
The accumulation of N, P, K, Ca, Mg, Fe, Mn, Zn, and B were determined
at transplanting, first flowering, first harvest, middle of harvest
season, and end of harvest season to ascertain the extent and the pattern
of plant nutrient uptake in strawberry (Fragaria x ananassa Duch.). The
plants were grown with the annual hill cultural system and mulched with
polyethylene. More accumulation of each element occurred during harvest
than before that time. Excluding harvested fruit, leaves accumulated the
most N, P, K, and Mg, the roots and crown the most Fe and Zn, while the
dead material accumulated the most Ca. Harvested fruit accumulated more
N, P, K, and B than did the plant. The calculated average seasonal
accumulation of the 9 elements in the plant and in the harvested fruit
during the 2 seasons in kg/ha were: K 63.1, N 58.6, Ca 30.8, P 9.4,
Mg 7.8, Fe 0.456, Mn 0.161, Zn 0.088, and B 0.077.
11. Albregts, E. E., and C. M. Howard. 1981. Effect of poultry manure on
strawberry fruiting response, soil nutrient changes, and leaching.
J. Amer. Soc, Hort. Sci. 106:295-298.
Strawberries (Fragaria x ananassa Duch.) were grown for 3 seasons on a
well drained fine sand which received 0, 4.5, 9, 18, and 36 Metric Tons
(MT)/ha of poultry manure annually. Fruit yields increased each season
with increased rates of manure up to 18 MT/ha. The 36 MT/ha rate caused
a foliage burn during the first three seasons which may have reduced
yields, Considerable leaching of the soluble nutrients from manure to
and below the 60 cm soil depth occurred from season to season. Analyses
of saturated soil extracts indicated that concentrations of soluble
salts, K, and N03-N increased with increasing rates of manure at all 4
depths to 60 cm. The Ca, K, and Mg concentrations at all 4 soil depths
increased with increased manure rates and generally decreased with depth.
Or-rnic matter content of the surface 15 cm of the soil increased with
increased manure rate. Soil pH was only slightly affected by the manure
12. Howard, C. M., and E. E. Albregts. 1981. An outbreak of Verticillium wilt
of strawberries in central Florida. Plant Disease (In Press).
Verticillium wilt of strawberries was found for the first time in central
Florida in 1981. Surveys showed that all infected plants came from two
nursery fields in Michigan. The greatest percent of wilt occurred in
plants that were grown in soil that had been in potatoes the previous
year and was fumigated with MB-C 98-2 rather than MB-C 67-33 before
setting the strawberries.
13. Howard, C. M., and E. E. Albregts. 1981. Cleistothecia of Sphaerotheca
macularis (powdery mildew) on strawberry plants in Florida. Plant
Disease (In Press).
Cleistothecia of Sphaerotheca macularis were found in 1981 for the first
time on strawberry plants in Florida. They were found only on plants
that were grown in Maine and Michigan and transplanted into Florida fruit
production fields. Benomyl 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 those
plants. Benomyl or sulfur controlled the disease on plants from those
14. Albregts, E. E., and C. M. Howard. 1981, Effect of intermittent sprinkler
irrigation on establishment of strawberry transplants. HortScience (In
Diurnal intermittent irrigation intervals (minutes on/minutes off) of
3/17, 5/25, 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 with
decreased length of the 'on interval.' Plant mortality was greater with
the 3/17 and 5/25 treatments. Seasonal fruit yield was reduced the first
season with the 5/25 treatment. January yield was reduced with the 3/17
and 5/25 treatments.
15. Albregts, E. E., and C. M. Howard. 1976. Effect of intermittent irrigation
and antitranspirants on establishing strawberry transplants on mulch.
Proc. Fla. State Hort. Soc. 89:85-86.
Trials were conducted for three seasons using continuous or intermittent
overhead sprinkler irrigation during daytime to establish strawberry
transplants in the fruiting field. In addition to continuous irrigation,
a thirty minute interval was used the first season, and a fifteen minute
interval was added in the second and third seasons. Antitranspirants were
included as treatments during the first two seasons. The cultivar
'Florida Belle' was used in all trials. Breeding lines 69-712 and 71-729
and cultivars 'Tioga' and 'Tioga Special' were used during various seasons.
Generally, the leaf surface of plants given fifteen or thirty minute
intermittent irrigation remained moist between irrigations. However, with
dry and windy conditions leaf surfaces were dry for as long as ten minutes
with the use of the thirty minute interval.
Overall, the use of antitranspirants did not enhance plant survival, leaf
retention, fruit size, or seasonal yield:. The use of intermittent irriga-
tion did not reduce leaf retention, plant survival, fruit size, or
seasonal yields compared to continuous irrigation. The results indicate
that as long as the plant can be kept moist and the mulch is moist or
cool (about 21 C) during the period of establishing transplants any
irrigation time interval could probably be used without reducing yields.
The use of intermittent irrigation saved more than one-half the irrigation
water applied to the continuously irrigated treatment.
16. Albregts, E. E., and C. M. Howard. 1977. The effect of planting date and
plant chilling on growth and fruiting responses of three strawberry
clones. Proc. Fla. State Hort. Soc. 90:278-280.
Strawberry plants of the clones 'Florida Belle,' 'Tufts,' and Florida 71-729
were chilled (36 F, 2 C) for 0, 15, and 30 days before transplanting in
fruiting field in 1975. In 1974, the 'Florida Belle' plants received the
same chilling treatments as in 1975; however, some of the chilling treatments
were not applied to the clones 'Tufts' and 71-729 in 1974. The plants were
set on September 15, October 1, October 15, and November 1 in 1974 and on
October 1, October 15, and November 1 in 1975. Chilling plants for 30 days
or setting on November 1 reduced early yields of all clones. Seasonal
yields with 'Florida Belle' were highest when set on October 1 or
October 15 in 1975-76 but were unaffected by planting date in 1974-75.
Seasonal yields were lowest with November 1 planting date. The clone
71-729 gave highest seasonal yields with the October 1 planting date,
but seasonal yields were unaffected by chilling. The best planting date
for 'Tufts' appears to be mid-October. Early planting and/or 30 day
chilling caused stolon production, especially with the 'Tufts' clone.
17. Otte, J. A., M. T. Pospichal, C. M. Howard, and E. E. Albregts. 1977.
Estimated Plant City area strawberry production costs. Proc. Fla. State
Hort. Soc. 90:234-236.
Estimating production costs is a management tool for growers. Cost data
can aid existing or new growers in obtaining credit. Plant City area
strawberry growers and grower supply dealers were surveyed to estimate
production costs. Estimates of the investment in land and equipment, of
the annual fixed costs, variable growing costs, and harvesting and
packing costs were determined for the 1977 crop. For a typical 20 acre
farm the estimated fixed and variable costs/acre were $1247 and $2269,
respectively. Harvesting and packing costs were estimated at $1.99/flat.
Estimated break-even prices to cover fixed, variable, harvesting, and
packing costs ranged from $4.50 per flat at a yield of 1400 flats per
acre to $3.75 per flat at a yield of 2000 flats per acre.
18. Albregts, E. E., and C. M. Howard. 1978. Influence of fertilizer sources
and drip irrigation on strawberries. Proc. Soil and Crop Sci. Soc. Fla.
Drip irrigation was applied to fruiting strawberries at rates of 5, 10,
and 20 mm/wk (bed area only), and all fertilizer was applied before
mulching with the N derived from four sources. Fertilizer placement was
either in the bed center or on bed shoulders. Irrigation rates had
little effect on yields and on soluble salts, N03-N, NH3-N, and K levels
in the top 60 cm of bed. However, fruit quality was poor with the lower
rates of drip irrigation. Fertilizer placement did not affect yields and
only affected soluble salts, N03-N, NH3-N, and K levels the first season.
Fertilizer sources did not affect seasonal fruit yields but did affect
soil solution concentrations. Soil solution soluble salts, N03-N, NH3-N,
and K were highest with the fertilizer treatments containing Osmocote
(18-6-12) or with NH4NO3 placed on a paper barrier, and lowest levels were
with fertilizer sources of ureaformaldehyde and NH4NO3. Soil soluble
salts, N03-N, NH3-N and K decreased with depth at most sampling dates.
19. Albregts, E. E., and C. M. Howard. 1978. Evaluation of plant density on
strawberry plant growth and fruiting response. Proc. Fla. State Hort.
Plants of 3 strawberry cultivars and one breeding line were evaluated
in the fruiting field for the effects of setting 1, 2, or 3 transplants
per planting hole on 2-row beds. Significantly higher yields were given
in some instances with higher plant densities. However, as plant density
increased the total amount of foliage and number of plant crowns also
increased, which made fruit harvest more difficult. In addition, as the
daily temperature increased in March and April, more fruit rot was
observed with increased plant density. The amount of fruit rot varied
with the clone. Fruit size was not affected by plant density.
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.
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