OCT 6 1953
POTATO INVESTIGATIONS LABORATORY MIMEO REPORT 54-1
Control Measures for Some Diseases of Vegetables in the Hastings Area
A. H. Eddins
Diseases of Cabbage, Cauliflower and Broccoli
Major diseases of cabbage, cauliflower and broccoli in the Hastings area are
Alternaria leaf spot, black rot, damping-off, downy mildew, soft rot and yellows.
Control measures which will reduce losses from these diseases are as follows:
1. Use black-rot-free seed from the Puget Sound area if obtainable.
Treat seed from other places with hot water for control of black
rot. Dust seed with arasan or semesan after treatment with hot
water to reduce losses from seed decay and preemergence damping-
2. Practice a 1-year rotation of seedbeds for control of black rot.
3. Cultivate seedbeds after heavy rains to promote areation of the
4. Use chloranil or nabam for control of downy mildew and Alternaria
leaf spot as recommended in Table 1.
5. Do not use imported plants as they may be affected with black rot,
yellows and other serious diseases. Do not use yellows-infested
soil for seedbeds.
6. Grow yellows-resistant varieties of cabbage on yellows-infested
land. Varieties recommended are Medium Copenhagen Resistant
(early) and Marion Market and Resistant Glory(midseason). Cauli-
flower and broccoli are resistant and can be grown safely in
7. Handle heads carefully to prevent unnecessary bruising and reject
all severely spotted, badly bruised and decayed heads for ship-
8. During hot weather precool heads immediately after cutting and
ship under refrigeration at 400 F.
9. Plow under left-over plants in plant beds and old plants and
refuse in harvested fields immediately after they are abandoned
to prevent spread of diseases from these locations to younger
cabbage plants in nearby seedbeds and fields.
Table 1.- Fungicides Recommended for Control of Downy Mildew and Alternaria Leaf
Spot of Cabbage, Cauliflower and Broccoli in the Hastings Area.
S4 lbs. 48% wettable
in 100 gals. water
2-qts. plus 1 lb.
zinc sulfate in
100 gals. water
Begin treatment before either disease is present
(usually within a week to 10 days after planting
seed) and repeat 2 or 3 times each week until
plants are set in the field. Quantities of spray
and dust required for treating small plants are
given in Table 2. Chloranil has given better
control of downy mildew under epidemic conditions
Use same application schedule and quantities of
spray as given in Table 2. Discontinue treat-
ment in seeded field when plants are thinned to
Transplanted and Thinned Fields
Begin treatment of plants 2 weeks before harvest
or prior to that time if Alternaria leaf spot is
developing and spreading rapidly. Apply 100 to
150 gals. of spray per acre every 6 to 7 days
depending on size of plants. Use a good commer-
cial spreader-sticker as recommended on the
*Chloranil is compatible with TEPP, parathion, DDT and chlordane. Nabam is
compatible with DDT, chlordane, toxaphene, TEPP and parathion.
Table 2.- Approximate Quantities of Chloranil and Nabam Sprays and Chloranil Dust
,to Use at Each Application for Control of Downy Mildew and Alternaria
Spot on Small Plants.
Narrow 2- to 3-Drill Row
Beds 40 to 42 Inches Apart Beds One Yard Wide
Plant Height Spray j Du.t Spray Dus
Gals. per Acre Lbs. per Acre Gals. per 100 Lbs. per 100
Sq. Yds. Sq. Yds.
Less than 2 inches 80 to 100 15 to 20 4 to 5 3/4 to 1
2 to 4 inches 100 to 120 20 to 25 5 to 6 1 to 1-
4 to 8 inches 120 to 150 25 to 35 6 to 7 ij to 2
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Late Blight of Potatoes
Late blight is the most important foliage and tuber disease of potatoes in
the Hastings area. It can be controlled with fungicides applied every 5 to 7 days
starting when the tops are 6 to 8 inches high or sooner if the disease is present.
Several fungicides including nabam, zineb, mandate and phygon, have given good con-
trol of the disease in test plots at the Potato Investigations Laboratory. Nabam
is used by most Hastings potato growers. It also is effective against Alternaria
leaf spot and downy mildew of cabbage.
Directions for making nabam spray are as follows:
1. Start running water in the sprayer tank with the agitator going.
2. Keep the agitator going while the spray is being mixed.
3. Pour in 2 quarts nabam(Dithane D14 or Parzate liquid) for each
100 gallons water after agitator is covered with water. Allow
at least one minute for the nabam to mix with the water.
4. Slowly pour in 3/4 to one pound of finely granulated or com-
pletely dissolved zinc sulfate(36 percent metallic zinc equiv-
lent) for each 100 gallons. Allow at least two minutes for
the zinc sulfate to react with the nabam.
5. Add 1 quart 25% DDT emulsion for each 100 gallons of spray for
aphis control on potatoes. Parathion or other aphicides are
used for controlling aphis on cabbage.
6. Finally, add a spreader-sticker if the spray is used on cabbage.
No spreader-sticker is needed if the spray is used on potatoes.
7. Keep agitator going in sprayer and auxiliary tanks as much as
possible until the spray is applied.
Materials Required to Make Different Quantities of Nabam Spray
Water Nabam Zinc Sulfate 25% DDT Emulsion
Gals. Quarts Pounds Quarts
100 2 3/4 to 1 1
200 4 li to 2 2
300 6 2- to 3 3
400 8 3 to 4 4
500 10 3 3/4 to 5 5