Late blight is a disease of tomato and potato caused by the fungus Phytophthora infestans, and tends to be most damaging to potato. However, the disease can also be serious on tomato when conditions are cool and rainy. The pathogen survives between cropping seasons in association with volunteers, cull piles and gardens. Spores can then be blown by wind from these sources to new plants. When the weather is favorable, infection can move so rapidly that affected plants appear as though damaged by frost.
Late blight can be very devastating to all aboveground plant parts of tomato. Leaf lesions first appear on as irregular, water-soaked spots, which enlarge rapidly into pale green to brown lesions, and cover large areas of the leaf. In moist weather, the lower surface of leaves with lesions may be covered with a gray to white moldy growth. Infected foliage becomes brown, shrivels, and soon dies. Petioles and stems are affected in a similar manner, so the entire plant may die. Fruit lesions appear as dark, green, greasy spots, which may enlarge until the entire fruit in invaded. A thin layer of white fungal growth may cover the fruit lesions during moist weather. Decaying vines will have a foul odor.
No effective biological control strategies have been developed for late blight.
Plant materials serve as inoculum sources for nearby fields. Cultural controls include elimination of potato cull piles in the vicinity of tomato plantings and destroying volunteer potato plants.
Fungicides can play a key role in the management of late blight in tomato, especially when the weather is favorable. Several late blight forecasting systems have been developed to help in the timing of fungicide sprays when inoculum is present and conditions threaten. Fungicides are most effective when used in combination with cultural control strategies.
Product List for Late Blight Tomato:
Pesticide |
Product per acre |
ApplicationFrequency
|
Remarks |
|
Copper Fungicides |
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|
Champ Dry Prill |
1.33 lb |
5-7 days |
|
|
Champ Formula 2 |
1.33 pt |
5-7 days |
|
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Copper-Count-N |
4-6 pt |
7 days |
|
|
Kocide 101 |
1.5-3 lbs |
5-7 days |
|
|
Kocide DF |
1.5-3 lbs |
5-7 days |
|
|
Kocide 4.5LF |
1-2 pts |
5-7 days |
|
|
Kocide 3000 |
0.75-1.75 lb |
5-10 days |
|
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Kocide 6000 |
0.75-1.75 lb |
5-10 days |
|
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Chlorothalonil and Chlorothaloni Mixtures |
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Bravo 720, Echo 720 |
1.5-3 pt |
7-14 days |
Do not graze or feed debris to livestock; 7 day PHI |
|
Bravo Ultrex, Echo 90DF |
1.7-2.2 lb |
7-10 days |
Maximum of 18.3 pounds per season; 0 day PHI |
|
Bravo Weather Stik |
1.5-3.0 pt |
7-10 days |
Maximum of 20 pints per season; 0 day PHI |
|
Echo Zn |
2-4 pt |
7-10 days |
Maximum of 3.6 gallons per season; 0 day PHI |
|
Ridomil Gold/Bravo |
2.0 lb |
14 days |
Maximum of three applications; 14 day PHI |
|
EBDC, Copper/EBDC, and EBDC/Zoxamide |
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Cuprofix MZ Disperss |
1.75-4.75 lb |
3-10 days |
Maximum of 21 pounds per season; 5 day PHI |
|
Dithane |
1.5-2.0 lb |
7-10 days |
Maximum of 8.5 pounds per season; 5 day PHI; use a non-ionic surfactant to improve performance |
|
Gavel |
1.5-2.0 lb |
7-10 days |
Maximum of 4 (west of Rockies) to 8 (east of Rockies) applications; 5 days PHI |
|
Maneb 75 DF |
1.5-2.0 lb |
7-10 days |
Maximum of 8.5 pounds per season; 5 day PHI |
|
Manex |
1.2-1.6 qt |
7-10 days |
Maximum of 6.4 quarts per season; 5 day PHI |
|
ManKocide |
2.5-5.0 lb |
7-10 days |
Maximum of 42.6 pounds per season; 5 day PHI |
|
Manzate Fl |
1.2-1. qt |
7-10 days |
Maximum of 6.4 qts per season; 5 day PHI |
|
Penncozeb 80W |
0.75-2.0 lb |
7-10 days |
Maximum of 8.0 pounds per season; 5 day PHI. |
|
Penncozeb 75DF |
0.75-2.0 lb |
7-10 days |
Maximum of 8.5 pounds per season; 5 day PHI. |
|
Strobilurin and Strobilurin Mixtures |
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Cabrio |
8-16 oz |
7-14 days |
Maximum of 6 applications or 96 oz per season; Do not make more than 2 applications before alternating with a fungicide with a different mode of action; 0 day PHI |
|
Flint |
4 oz |
7-10 days |
Maximum of 5 applications or 16 ounces per season; Rotate with fungicides with a different mode of action such as Maneb, Bravo, or copper-containing products; 3 day PHI |
|
Quadris |
6 oz |
5-7 days |
Maximum of 5 applications or 0.60 lb a.i.per season; Alternate Quadris with fungicides with different modes of action; 0 day PHI |
|
Tanos |
8 oz |
5-7 days |
Rotate and rotate with fungicides with a different mode of action such as chlorothalonil or mancozeb; Maximum of 72 ounces per season; 3 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: Eggplant, Pepper, Tomato, Disease, Late Blight
Date: 04/01/2007