Anthracnose of cucurbits is caused by the fungus Colletotrichum orbiculare. The disease is fairly common on the foliage and fruit of melon and cucumber in warm, humid weather, but squash and pumpkin are less susceptible. The disease can be initiated by seedborne inoculum, infected volunteers, and infested crop debris. Wind, splashing rain and irrigation water, field workers, and equipment can spread spores (conidia), but free moisture is essential for conidia to germinate and infect plants. Disease symptoms appear about 4 days after infection. Anthracnose is most severe during humid, rainy weather during moderate to warm (72 to 80ºF) temperatures. The pathogen survives between cucurbit crops in contaminated seed, infected volunteers, and in infested crop debris.
Anthracnose symptoms can develop on leaves, petioles, stems, and fruit. Leaf lesions first appear near veins as circular, light brown to reddish spots up to 0.4 inches in diameter. The centers of lesions sometimes fall out, giving infected leaves shot-hole appearance. Infected leaves also can become deformed. Petiole and stem lesions are shallow, elongated, and tan to dark in color. Sometimes red exudate is produced from petiole and stem lesions on melon.
Fruit lesions are circular, sunken, and water-soaked, and appear as the fruit nears maturity. Lesions continue to enlarge as fruit matures, and can become several inches or larger in diameter. During humid, wet weather, fruit lesions turn black and are covered with pink spore masses. Anthracnose can reduce fruit yield, quality, and marketability.
No biological control practices have been developed for anthracnose.
Only high quality seed free from the anthracnose pathogen should be planted. Practice a three-year or longer crop rotation to nonhosts such as small grains or corn. Crop debris should be promptly and thoroughly incorporated after harvest to reduce pathogen overwintering that can initiate epidemics the following year. Many cucumber and watermelon varieties are resistant to many or all races of the anthracnose pathogen and should be planted if anthracnose is a recurrent problem. Anthracnose resistance in other melons has not been developed.
Chemical controls are most effective when combined with sound cultural practices.
Product List for Anthracnose:
Pesticide |
Product per acre |
Application Frequency
|
Remarks |
Captan |
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Captan 4F |
4 pt |
5-7 days |
4 day REI |
|
Captan 50 |
4 lb |
5-7 days |
4 day REI |
|
Chlorothalonil and Chlorothalonil Mixtures |
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Bravo 720 |
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|
Do not graze or feed debris to livestock; 7 day PHI |
|
Bravo Ultrex |
1.4-1.8 lb |
7-10 days |
Maximum of 16.5 pounds per season; 0 day PHI |
|
Bravo WeatherStik |
1.5-2.0 pt |
7-10 days |
Maximum of 20 pints per season; 0 day PHI |
|
Echo 720 |
1.5-2.0 pt |
7-10 days |
Maximum of 2.5 gallons per season; 7 day PHI |
|
Echo 90DF |
1.2-1.6 lb |
7-10 days |
Maximum of 16.67 pounds per season; 7 day PHI |
|
Echo Zn |
2.2 to 2.8 pt |
7-10 days |
Maximum of 3.6 gallons per season; 7 day PHI |
|
Ridomil/Bravo |
1-2 lb |
7-14 days |
7 day PHI |
Copper Fungicides |
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Champ Dry Prill |
1.33 lb |
5-7 days |
|
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Champ Formula 2 |
1.33 pt |
5-7 days |
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Copper-Count-N |
4-6 pt |
7 days |
Mid-harvest. |
|
Kocide 101 |
1.5-3 lbs |
5-7 days |
May cause injury |
|
Kocide DF |
1.5-3 lbs |
5-7 days |
May cause injury |
|
Kocide 4.5LF |
1-2 pts |
5-7 days |
May cause injury |
|
Kocide 3000 |
0.5-1.25 lb |
5-7 days |
May cause injury |
|
Nordox |
1.5-2.0 lb |
7-10 days |
|
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Tri Basic Copper |
2-4 pt |
7-10 days |
1 day PHI |
EBDC, Copper/EBDC, and EBDC/Zoxamide Mixtures |
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Cuprofix MZ Disperss |
4-7.25 lb |
3-10 days |
Maximum of 63.1 pounds per season; 5 day PHI |
|
Dithane |
2-3 lb |
7-10 days |
Maximum of 25.6 pounds per season; 5 day PHI; use a non-ionic surfactant to improve performance |
|
Gavel 75DF |
1.5-2.0 lb |
7-10 days |
Maximum 16 pounds per season; 5 day PHI; include a nonionic surfactant to improve performance |
|
Maneb 75 DF |
1.5-2.0 lb |
7-10 days |
Maximum of 17.1 pounds per season; 5 day PHI |
|
Manex 80W |
1.5-2.0 lb |
7-10 days |
Maximum of 16.0 pounds per season; 5 day PHI |
|
Manex |
2.4-3.2 pt |
7-10 days |
Maximum of 25 pints per season; 5 day PHI |
|
ManKocide |
2.0-2.5 lb |
7-10 days |
Maximum of 128 pounds per season; 5 day PHI |
|
Penncozeb 80W |
1.5-3.0 lb |
7-10 days |
Maximum of 24.0 pounds per season; 5 day PHI |
|
Penncozeb 75DF |
1.5-3.0 lb |
7-10 days |
Maximum of 25.6 pounds per season; 5 day PHI |
Strobilurins and Strobilurin Mixtures |
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Cabrio |
12-16 oz |
7-14 days |
Maximum of 4 applications or 64 oz per season; Alternate with different modes of action; 0 day PHI |
|
Quadris |
11.0-15.4 fl oz |
5-14 days |
Maximum of 4 applications or 2.88 quarts per season; Alternate Quadris with fungicides with different modes of action; 1 day PHI |
|
Tanos |
8 oz |
5-7 days |
Rotate with fungicides with a different mode of action, such as chlorothalonil or mancozeb; Maximum of 48 ounces per season; 3 day PHI |
|
Thiophanate Methyl |
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Topsin M 70WP |
0.5 lb |
7-14 days |
Maximum of 3 lb per season; Alternate fungicide sprays or tank-mix with fungicides with a different mode of action; 1 day PHI |
|
Topsin 4.5 FL |
10 fl oz |
7 days |
Maximum of 60 fl oz per season; Alternate fungicide sprays or tank-mix with fungicides with a different mode of action; 1 day PHI |
|
Topsin WSB |
0.5 lb |
7-14 days |
Maximum of 3 lb per season; Alternate fungicide sprays or tank-mix with fungicides with a different mode of action; 1 day PHI |
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The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Cucurbits, Disease, Anthracnose, Cucumber, Melon, Pumpkin, Squash, Zucchini
Date: 04/01/2007