Extension Circular 69-1849: Vegetable diseases, II- An aid to identification and control

Weihing, J.

Wysong, D.

English

DigitalCommons@University of Nebraska

University of Nebraska - LincolnDigitalCommons@University of Nebraska - LincolnHistorical Materials from University of Nebraska-Lincoln Extension Extension1969EC69-1849 Vegetable Diseases, II : An Aid toIdentification and ControlD. WysongJ. WeihingFollow this and additional works at: http://digitalcommons.unl.edu/extensionhistThis Article is brought to you for free and open access by the Extension at DigitalCommons@University of Nebraska - Lincoln. It has been accepted forinclusion in Historical Materials from University of Nebraska-Lincoln Extension by an authorized administrator of DigitalCommons@University ofNebraska - Lincoln.Wysong, D. and Weihing, J., "EC69-1849 Vegetable Diseases, II : An Aid to Identification and Control" (1969). Historical Materialsfrom University of Nebraska-Lincoln Extension. 3939.http://digitalcommons.unl.edu/extensionhist/3939Ac:lR I s 85~ E. C. 69-1849 &7 #(;-;<(~/81'1 VEGETABLE DISEASES, (dJJ~~ J An Aid to Identification and C~~ctrol cf:... . \... .. LJ 5 D. S. Wysong and J. L. Weihing Agricultural Extension Plant Pathologists 1. STEM ANTHRACNOSE: Col/etotrichum truncatum. Occurs rarely on bean and lima bean in Nebraska. Infected plants appear chlorotic and stunted. Brick red spots occur on leaves, petioles, and stems. Initial small, red spots on the pods may result in pod drop, or may spread over the entire surface. Captan, maneb, or zineb are suggested fungicides when controls are justified. 2. MOSAIC: virus. Commonly occurs on many of the vine crops. Yellow-green and dark-green mottling of the leaves with a general stunting or "bunching" of entire plant. Fruit may be warty or knobby. Control aphids ahd cucumber beetles which transmit the viruses with malathion and Sevin or methoxychlor. 3. BACTERIAL SPOT: Xanthomonas vesicatoria. Rarely seen in Nebraska. This disease is characterized by wart-like, raised pimples on the leaves, promptly turning dry and brown. Affected leaves become yellow and drop. Spots on the fruit are blister-like and rough. If the disease is severe, a rotation program of at least three years in both seedbed and transplant field should be followed. 4. DOWNY Ml LDEW: Peronospora parasitica. Rarely seen on cabbage or other crucifers in Nebraska. Under cool, moist conditions leaf spots enlarge indefinitely to form yellow areas on upper side and fluffy white mildew on the lower side. Leaves will turn purple to brown, wilt and die. Avoid overcrowding and sprinkling of foliage. During cool, rainy periods, apply chloranil, maneb, or zineb at 5-day intervals. 5. LETTUCE DROP: Sc!erotinia spp. This disease may be troublesome wherever head lettuce is grown. It appears in mid-season or later as a progressive wilting of leaves beginning with the older, lowermost leaves and continuing until the head collapses. May be foul smelling, slimy, or covered with a dense white, gray, or blue-green mold. Polyethylene mulches reduce head drop. Terraclor as a spray or dust applied when plants are 2-3 inches tall aids in disease control. Plow down crop refuse after harvest. 6. FUSARIUM WILT: Fusarium oxysporum f. batatas. A serious disease in commercial production areas. The soil-inhabiting fungus enters through vascular wounds in freshly cut stems or roots. Leaves become yellow between the veins and drop. When infected stems are split, the vascular bundles appear purple, later becoming blackened. Discoloration may extend into the "potato," appearing as a dark ring beneath the skin. Use of resistant varieties and crop rotation are the control measures suggested by workers in the field. 7. WHITE LEAF SPOT: Cercospora a/bomaculans. Usually considered of minor importance, this disease appears as tiny water-soaked spots that bleach into circular, slightly collapsed lesions up to one quarter of an inch in diameter. These may become gray to tan and coalesce. Where practical, apply zineb or maneb several times during rainy periods. 8. RUST: Uromyces phaseoli typica. Occasionally seen in Nebraska on dry and snap beans. The disease appears on leaves as small, slightly raised spots, enlarging to form brownish pustules about 1/16 inch in diameter. Infected leaves may yellow, wither, and fall early. Bean varieties resistant or tolerant to many races of rust have been developed. Where necessary, several weekly applications of zineb, thiram, ziram or sulfur have provided effective control. 9. SCAB: Streptomyces scabies. This disease is commonly found in home gardens as well as in fields for commercial production. The disease is characterized by shallow or deep, rough, russeted, raised or pitted, corky areas on the tuber skin. The lesions vary widely in size and shape and usually are darker colored than the surrounding healthy skin. Control is achieved by treating the uncut potatoes in a hot formaldehyde solution ( 1 pint in 15 gal. of water at 1210F.) for 3-4 minutes or by treating whole or cut seed-pieces in organic mercury dips such as Semesan Bel. EXTENSION SERVICE UNIVERSITY OF NEBRASKA COLLEGE OF AGRICULTURE AND HOME ECONOMICS AND U.S. DEPARTMENT OF AGRICULTURE COOPERATING E. F. FROLIK. DEAN J. L. ADAMS, DIRECTOR CE 8 I. VEGETABLE DISEASES, II An Aid to Identification and Control May 1968 STEM ANTHRACNOSE OF LIMA BEAN 2. SQUASH MOSAIC ON LEAF AND YOUNG FRUIT 3. BACTERIAL SPOT OF PEPPER 4. DOWNY MILDEW OF CABBAGE 5. LETTUCE DROP 6. FUSARIUM WILT OF SWEET POTATO Inset shows stem damage 7. Inset shows Alternaria following damage WHITE LEAF SPOT OF TURNIP 8. RUST OF SNAPBEAN 9. SCAB OF IRISH POTATO PREPARED BY THE CLEMSON UNIVERS ITY COOPERATIVE EXTENSION SERVICE'S ENTOMOLOGY • PLANT PATHOLOGY AND AGRICULTURAL COMM UNICATI ONS SECTIONS, FEDERAL EXTENSION SERVICE COOPERATING 

EC69-1849  Vegetable Diseases, II : An Aid to Identification and Control

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University of Nebraska - Lincoln
DigitalCommons@University of Nebraska - Lincoln
Historical Materials from University of Nebraska-
Lincoln Extension Extension
1969
EC69-1849 Vegetable Diseases, II : An Aid to
Identification and Control
D. Wysong
J. Weihing
Follow this and additional works at: http://digitalcommons.unl.edu/extensionhist
This Article is brought to you for free and open access by the Extension at DigitalCommons@University of Nebraska - Lincoln. It has been accepted for
inclusion in Historical Materials from University of Nebraska-Lincoln Extension by an authorized administrator of DigitalCommons@University of
Nebraska - Lincoln.
Wysong, D. and Weihing, J., "EC69-1849 Vegetable Diseases, II : An Aid to Identification and Control" (1969). Historical Materials
from University of Nebraska-Lincoln Extension. 3939.
http://digitalcommons.unl.edu/extensionhist/3939
Ac:lR I 
s 
85~ E. C. 69-1849 
&7 
#(;-;<(~/81'1 
VEGETABLE DISEASES, (dJJ~~ J 
An Aid to Identification and C~~ctrol 
cf:... 
. \... .. LJ 5 
D. S. Wysong and J. L. Weihing 
Agricultural Extension Plant Pathologists 
1. STEM ANTHRACNOSE: Col/etotrichum 
truncatum. Occurs rarely on bean and lima bean in 
Nebraska. Infected plants appear chlorotic and 
stunted. Brick red spots occur on leaves, petioles, and 
stems. Initial small, red spots on the pods may result 
in pod drop, or may spread over the entire surface. 
Captan, maneb, or zineb are suggested fungicides 
when controls are justified. 
2. MOSAIC: virus. Commonly occurs on many of 
the vine crops. Yellow-green and dark-green mottling 
of the leaves with a general stunting or "bunching" of 
entire plant. Fruit may be warty or knobby. Control 
aphids ahd cucumber beetles which transmit the 
viruses with malathion and Sevin or methoxychlor. 
3. BACTERIAL SPOT: Xanthomonas vesicatoria. 
Rarely seen in Nebraska. This disease is characterized 
by wart-like, raised pimples on the leaves, promptly 
turning dry and brown. Affected leaves become 
yellow and drop. Spots on the fruit are blister-like 
and rough. If the disease is severe, a rotation program 
of at least three years in both seedbed and transplant 
field should be followed. 
4. DOWNY Ml LDEW: Peronospora parasitica. 
Rarely seen on cabbage or other crucifers in 
Nebraska. Under cool, moist conditions leaf spots 
enlarge indefinitely to form yellow areas on upper 
side and fluffy white mildew on the lower side. 
Leaves will turn purple to brown, wilt and die. Avoid 
overcrowding and sprinkling of foliage. During cool, 
rainy periods, apply chloranil, maneb, or zineb at 
5-day intervals. 
5. LETTUCE DROP: Sc!erotinia spp. This disease 
may be troublesome wherever head lettuce is grown. 
It appears in mid-season or later as a progressive 
wilting of leaves beginning with the older, lowermost 
leaves and continuing until the head collapses. May be 
foul smelling, slimy, or covered with a dense white, 
gray, or blue-green mold. Polyethylene mulches 
reduce head drop. Terraclor as a spray or dust applied 
when plants are 2-3 inches tall aids in disease control. 
Plow down crop refuse after harvest. 
6. FUSARIUM WILT: Fusarium oxysporum f. 
batatas. A serious disease in commercial production 
areas. The soil-inhabiting fungus enters through 
vascular wounds in freshly cut stems or roots. Leaves 
become yellow between the veins and drop. When 
infected stems are split, the vascular bundles appear 
purple, later becoming blackened. Discoloration may 
extend into the "potato," appearing as a dark ring 
beneath the skin. Use of resistant varieties and crop 
rotation are the control measures suggested by 
workers in the field. 
7. WHITE LEAF SPOT: Cercospora 
a/bomaculans. Usually considered of minor 
importance, this disease appears as tiny water-soaked 
spots that bleach into circular, slightly collapsed 
lesions up to one quarter of an inch in diameter. 
These may become gray to tan and coalesce. Where 
practical, apply zineb or maneb several times during 
rainy periods. 
8. RUST: Uromyces phaseoli typica. Occasionally 
seen in Nebraska on dry and snap beans. The disease 
appears on leaves as small, slightly raised spots, 
enlarging to form brownish pustules about 1/16 inch 
in diameter. Infected leaves may yellow, wither, and 
fall early. Bean varieties resistant or tolerant to many 
races of rust have been developed. Where necessary, 
several weekly applications of zineb, thiram, ziram or 
sulfur have provided effective control. 
9. SCAB: Streptomyces scabies. This disease is 
commonly found in home gardens as well as in fields 
for commercial production. The disease is 
characterized by shallow or deep, rough, russeted, 
raised or pitted, corky areas on the tuber skin. The 
lesions vary widely in size and shape and usually are 
darker colored than the surrounding healthy skin. 
Control is achieved by treating the uncut potatoes in 
a hot formaldehyde solution ( 1 pint in 15 gal. of 
water at 1210F.) for 3-4 minutes or by treating whole 
or cut seed-pieces in organic mercury dips such as 
Semesan Bel. 
EXTENSION SERVICE 
UNIVERSITY OF NEBRASKA COLLEGE OF AGRICULTURE AND HOME ECONOMICS 
AND U.S. DEPARTMENT OF AGRICULTURE COOPERATING 
E. F. FROLIK. DEAN J. L. ADAMS, DIRECTOR 
CE 8 
I. 
VEGETABLE DISEASES, II 
An Aid to Identification and Control 
May 1968 
STEM ANTHRACNOSE OF 
LIMA BEAN 
2. SQUASH MOSAIC ON LEAF AND 
YOUNG FRUIT 
3. BACTERIAL SPOT OF PEPPER 
4. DOWNY MILDEW OF CABBAGE 5. LETTUCE DROP 6. FUSARIUM WILT OF SWEET POTATO 
Inset shows stem damage 
7. 
Inset shows Alternaria following damage 
WHITE LEAF SPOT OF 
TURNIP 
8. RUST OF SNAPBEAN 9. SCAB OF IRISH POTATO 
PREPARED BY THE CLEMSON UNIVERS ITY COOPERATIVE EXTENSION SERVICE'S ENTOMOLOGY • PLANT PATHOLOGY AND AGRICULTURAL 
COMM UNICATI ONS SECTIONS, FEDERAL EXTENSION SERVICE COOPERATING 


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EC69-1849 Vegetable Diseases, II : An Aid to Identification and Control

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