Title: Vegetarian
Full Citation
Permanent Link: http://ufdc.ufl.edu/UF00087399/00057
 Material Information
Title: Vegetarian
Series Title: Vegetarian
Physical Description: Serial
Creator: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publisher: Horticultural Sciences Department, Institute of Food and Agricultural Sciences, University of Florida
Publication Date: April 1968
 Record Information
Bibliographic ID: UF00087399
Volume ID: VID00057
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.


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Vegetable Crops Department


April 8, 1968

NO: 80


1. Poor Control of Tomato Late Blight
2. Plant Row Orientation
3. Seeding in Furrow and Herbicide Use
4. Cabbage Looper Control
5. Lime Effects on Watermelon Wilt
6. New Leafspot Disease on Cucumbers

1. Poor Control of Tomato Late Blight

Reports from several tomato areas in Florida during early 1968 indicate
that growers experienced considerable difficulty in controlling late blight
on this crop. The first reactions to failure in disease control are to in-
crease the amount of a fungicide each time it is applied, to combine two or
more fungicides, to increase the number of applications, to look for other
fungicides, or to combine two or more of these practices.

In many cases none of the above mentioned practices results in good
tomato blight control. This failure, more often than not, is in the technique
of application. This statement is supported by recent work conducted by Dr.
Robert A. Conover, plant pathologist and head of the Sub-Tropical Experiment
Station at Homestead, Florida. Dr. Conover tested several of the commonly
recommended fungicides under conditions where every third row was left unsprayed
to insure sufficient innoculum for a good test. He reported that unsprayed
plots were almost completely defoliated by late blight. On the other hand,
all of the recommended fungicides gave good protection of the sprayed plots.

Dr. Conover advises growers to check the whole spraying operation to be
sure that the sprayer is properly calibrated and properly operated. He points
out that too often speed is excessive, nozzle arrangement is poor and pressure
so high that penetration into the center of the plant is inadequate.

If you are a tomato grower having trouble with control of late blight,
check your spray operation carefully. It probably is not the fault of the
fungicide but caused by poor spraying techniques.

2. Plant Row Orientation

Should a grower lay out vegetable rows in a north-south or an east-west
direction? The answer to such a question is not an easy one. It would depend
on a number of factors such as season, crop, use of single or double rows, etc.


The southerly slope of a row oriented in an east-west direction in winter
is considerably warmer throughout the daylight hours than the northerly slope
of the same bed. On a bed oriented In a north-south direction the east side
is warmer than the west side in morning hours, but the reverse -is true In the
afternoon. In both cases, diffeftnces In temperatures are conditioned by the
angle of incidence of sunlight to the, bed. .. .;

As days lengthen and the sun moves directly overhead, the two sides of
east-west beds are more uniformly heated than a similar row orientation in
winter. However, the north-south orientation shqws the same general heat
pattern in summer as it does in winter.

On a raised, single row, bdd a crop might well benefit from the increased
heat accumulated on the south side of the bed during the winter months. On a
two row bed an east-west orientation may be undesirable because differences in
soil heat on the two sides may result in differences in growth patterns of the
two rows of plants. This difference is;often great enough to cause considerable
changes in height and yield of one row.over the other.

Sometimes the effect of bed orientation is directly on the plant. Tomatoes
planted in an east-west direction in the early spring show more physiological
leaf roll on the south side of the plant than on the north side. If, under the
same growing conditions, tomatoes are planted in a north-south direction, the
difference in leaf roll from one side of the plant to the other will be consider-
ably less since the period of heating changes from morning to afternoon from one
side to the other. From this standpoint a north-south direction may be desirable.

Briefly stamrized, bed-orientation can have important effects on growth,
maturity, yield, etc., of vegetables. The grower must decide which factors he
considers most important and use a bed-orientation to fit this need.

3. Seeding in Furrow and Herbicids Use

Reports of Injury to direct seeded tomatoes from the use of herbicides can
be traced to the method of seeding according to Mr. D. S. Burgis, Assistant
Horticulturist at the Gulf Coast Experiment Station at Bradenton. Tomatoes, as
well as many other crops, seeded in a furrow are apt to be injured by herbicides
if rains follow within 7 to 8 days of seeding and herbicide application.

Mr. Burgis explains that rains have a tendency to wash the herbicide-
treated soils from the sloping side of the furrow to the center of the furrow
where the seeds were planted. This results in a concentration of herbicides
right over the seed drill where emerging seedllng,.may be injured from excessive
amounts of an herbicide. Mr. Burgis reomomnds seedirg so that -he top of the
row is left flat or sloping away to the water furrow.

4. Cabbage Looper Control .

Dr. G. L. Greene of the Central Florida Experiment Station at Sanford
reported some interesting observations on cabbage looper control. He observed
that loogers develop faster and are more numerous when daily temperatures are
above 50 F. He noted looper populations on cabbage plants vary according to
the plant growth. Looper populations begin to increase 2 to 3 weeks after plants
are set in the field and continue to increase until cabbage is about half grown.
The almost grown, large larvae are commonly present at harvest.

Dr. Greene points this out to emphasize the importance of timing in
looper control. Loopers are easiest to kill when they first hatch. A skip
in spraying may permit a batch of larvae to increase in size and ultimately
do considerable damage to cabbage.

The following table gives distribution of looper eggs and larvae on
cabbage plants:

Leaf Surface Leaf Surface
Cabbage Looper Lower Upper Margin Internal

Eggs 85% 15% 64% 36%

Larvae 69/ 31%

This data illustrates another important point and that is the importance
of coverage. Nozzles must be directed to the lower as well as the upper leaf
surfaces. An insecticide placed near the eggs is more apt to kill the young
looper larvae than otherwise and since 85% of the eggs are deposited on the
lower leaf surfaces, coverage of that area of the leaf is most important.

5. Lime Effects on Watermelon Wilt

Recent research studies by Dr. Everett and Dr. Blasquez of the South
Florida Field Laboratory at Immokalee demonstrated a strong relationship
between lime and Fusarium wilt in watermelons. These two researchers applied
four rates of lime to virgin soil which was artificially innoculated with
Races I and 2 of the watermelon Fusarium fungus. Resulting pH values were
4.6 (no lime), 5.5 (3,000 lbs. lime), 6.0 (6,000 lbs. lime) and 6.5 (9,000 lbs.
lime). Stand counts varied from 6.2% on the low pH (no lime) plots to 85.5%
on the pH 6.5 (9,000 lbs. lime) plots. Marketable watermelon yields ranged
from zero at the lowest pH to 13.8 tons on the high pH plots.

Additional work from source and pH studies in the greenhouse indicates that
the effect is the result of pH and not so much a response to calcium. However,
this does not detract from the importance of calcium since research and experience
attest to the importance of this-element in the overall nutrition of the watermelon
Although requiring more work, this research points quite strongly to the
value of liming for watermelons. The lime-Fusarium wilt relationship combined
with the nutritional requirements of calcium and magnesium by watermelons makes
a good liming program for this crop gain greater importance than ever before.

6. New Leafspot Disease on Cucumbers

Dr. Blasquez of the South Florida Field Laboratory at Immokalee found a
new leafspot disease on cucumbers last spring. The causal organism is a fungus
identified as Cornynespora melonis (Cooke) Lindan. Preliminary spray tests
indicate that maneb at I to 2 lbs/100 gallons of water per acre gives good
control. Another material, Daconil, which is not approved for use as yet on
cukes gave excellent control. No resistance was found among ten test varieties
of cukes.

This disease as such ;s rather new to Florida and much has to be learned
about it. Whether or not it will become a serious pest is not known. Growers
observing leafspot diseases which are unfamiliar in appearance or in response
to spray should contact their county agricultural agents.


James Montelaro
Vegetable Crops Specialist

Mason E. Marvel F. S. jison, Chairman
Associate Vegetable Crops Specialist Vegetable Crops Department

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