Agriculture
Table 2. Date when Alternaria blight first appeared on muskmelons (cantaloupes) for successive years after muskmelons were grown repeatedly in the same field (from 1977 through 1981).
The results provide a clear indication of the value of rotations relative to diseases caused by pathogens that can survive either in soil or in association with refuse from diseased plants. Many vegetable diseases are in this category.
Traditional wisdom and common-sense, combined with results such as those presented in tables above, tell us that rotations are important. Interpretation of results from various field, greenhouse and lab studies, and observations by many plant pathologists, suggest a minimum number of years that a grower should avoid growing crops affected by specific diseases (See Table 3). All vegetable growers should consider this information seriously as they plan crop rotations within their disease management programs.
Table 3. Minimum years to avoid crops susceptible to specific diseases.
Article adopted from
Vegetable MD Online For original article 
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Agriculture
Do Rotations Matter within Disease Management Programs?
As agricultural land becomes more scarce, existing farms become more specialized, and land closest to roadside markets increases in value, in part due to the advertisement-value of growing some crops where they can be seen and/or harvested by customers, an increasing number of farmers are considering shorter rotations for some of their plantings. Indeed, it can be very tempting to shorten rotations. 
What would happen if one were to ignore rotations, that is, if one were to plant the same crop in the same field year after year? This was done in Penn State research fields for both tomatoes and for muskmelons. The results are summarized below in Table 1 (tomato early blight) and Table 2 (muskmelon/cantaloupe Alternaria blight).
Table 1. Defoliation associated with Alternaria early blight on tomatoes after growing tomatoes in the same field for 1, 2, 3, and 4 successive years).What would happen if one were to ignore rotations, that is, if one were to plant the same crop in the same field year after year? This was done in Penn State research fields for both tomatoes and for muskmelons. The results are summarized below in Table 1 (tomato early blight) and Table 2 (muskmelon/cantaloupe Alternaria blight). | Successive Years | % Defoliation when 5% Fruit were Ripe |
| Year 1 | 3 |
| Year 2 | 30 |
| Year 3 | 74 |
| Year 4 | 70 |
Table 2. Date when Alternaria blight first appeared on muskmelons (cantaloupes) for successive years after muskmelons were grown repeatedly in the same field (from 1977 through 1981).
| Successive Years | Years Grown | First Date when Alternaria Blight was first observed | # Days before August 8 | # Days after June 1 |
| Year 1 | 0 | August 8 | 0 | 69 |
| Year 2 | 1 | August 3 | 5 | 64 |
| Year 3 | 2 | July 29 | 10 | 59 |
| Year 4 | 3 | July 25 | 14 | 55 |
| Year 5 | 4 | July 18 | 21 | 48 |
The results provide a clear indication of the value of rotations relative to diseases caused by pathogens that can survive either in soil or in association with refuse from diseased plants. Many vegetable diseases are in this category.
Traditional wisdom and common-sense, combined with results such as those presented in tables above, tell us that rotations are important. Interpretation of results from various field, greenhouse and lab studies, and observations by many plant pathologists, suggest a minimum number of years that a grower should avoid growing crops affected by specific diseases (See Table 3). All vegetable growers should consider this information seriously as they plan crop rotations within their disease management programs.
Table 3. Minimum years to avoid crops susceptible to specific diseases.
| Vegetable | Disease | Period without a susceptible crop |
| Asparagus | Fusarium wilt & root rot | Indefinite; do not plant without fumigation |
| Beans | Root rots | 3 years; use grain crops, including sweet corn in rotation |
| White mold, Sclerotinia | 3 years; avoid tomato, potato, lettuce,cabbage, celery, carrot | |
| Anthracnose | 2 years | |
| Bacterial blight | 2 years | |
| Beets | Cercospora leaf spot | 3 years |
| Root rots | 3 years; use grain crops, including sweet corn in rotation | |
| Cabbage-related plants | Clubroot | 7 years; avoid turnip, radish; adjust pH to 6.8 or above |
| Fusarium yellows | Many years | |
| Blackleg | 3-4 years; avoid turnip | |
| Black rot | 2-3 years; avoid turnip | |
| White mold | 3 years; use grains crops, including sweet corn in rotation | |
| Carrots | Leaf blights (fungal & bacterial) | 2-3 years |
| Celery | Leaf blights | 2 years |
| Corn, sweet | Smut | 2-3 years |
| Yellow leaf blight | 3 years | |
| Northern leaf blight | 2 years | |
| Cucumber | Scab, GSB, & leaf spots | 2 years |
| Eggplant | Verticillium wilt | 4-5 years; avoid tomato, potato, pepper, strawberry, brambles |
| Fruit rots | 3 years | |
| Lettuce | Bottom rot (Rhizoctonia) | 3 years |
| Drop, Sclerotinia | 3 years; avoid tomato, potato, beans, cabbage, celery, carrot | |
| Muskmelon=cantaloupe &Watermelon | Leaf spots, GSB, & scab | 2+ years; avoid other cucurbits |
| Fusarium wilt | 4+ years; watermelon Fus. wilt is different | |
| Gummy stem blight (GSB) | 2 years; avoid muskmelon, pumpkin, squash | |
| Fusarium wilt | 4+ years; muskmelon Fus. wilt is different | |
| Onion | Leaf blights | 1-2 years |
| Parsley | Damping-off | 3 years |
| Parsnip | Leaf spot & root canker | 1 to 2 years |
| Peas | Root rots | 3 to 4 years |
| Fusarium wilt | 4 to 5 years | |
| Peppers | Bacterial spot | 2 years |
| Phytophthora blight | 3 years; avoid tomato, eggplant, cucurbits | |
| Potato | Verticillium wilt | 3-4 years without tomato, eggplant, pepper |
| Sclerotinia stalk rot | 4 years; avoid tomato, lettuce, beans, cabbage, celery, carrot | |
| Rhizoctonia canker | 2-3 years; best with 2 yr. grass or 1 yr cereal | |
| Silver Scurf | 2 years; primarily from seed tubers | |
| Early blight | 2 years; avoid tomato | |
| Pythium leak; pink rot | 4 years | |
| Common scab | 2-3 years; no root crops; adjust pH to 5.2 or below | |
| Pumpkin, & Winter squash | Angular leaf spot | 1-2 years |
| Black rot (GSB) | 2+ years; avoid muskmelon, watermelon, and other cucurbits | |
| Fusarium crown and fruit rot | 3 years; avoid other cucurbits | |
| Phytophthora blight | 3 years; avoid tomato, pepper, eggplant, and other cucurbits | |
| Scab | 2 years | |
| Radish | Clubroot | 7 years; avoid turnip, cabbage-related plants; adjust pH to 6.8 |
| Turnip | Clubroot | 7 years; avoid radish, cabbage-related plants; adjust pH to 6.8 |
| Spinach | Downy mildew & white rust | 2 years |
| Sweet potato | Black rot & scurf | 3 years |
| Pox (soil rot) | Few years; reduce soil pH below 5.2 | |
| Tomato | Bacterial canker | 3+ years |
| Bacterial spot | 2 years; avoid pepper | |
| Bacterial speck | 1 year | |
| Early blight | 2 years; avoid potato | |
| Anthracnose | 2-3 years; avoid potato | |
| Septoria leaf spot | 1-2 years | |
| Fusarium wilt | 3 years | |
| Verticillium wilt | Several years; longest possible; avoid potato and eggplant |
Article adopted from
Vegetable MD Online For original article - Fire Blight
By Laura Pottorff, Colorado State University Cooperative Extension agent, horticulture/plant pathology It's hard to even think it, but Spring sometimes can be a mixed blessing. Just ask the homeowner who's trying to cope with a laundry list of...
- Pepper Plant Blight: Information For Controlling Phytophthora On Peppers
By Kristi Waterworth The soil is full of living things, some useful, like earthworms, and others not as useful, like the fungi in the genus Phytophthora. These irksome pathogens can last long after infected plants have composted into nothing, continuing...
- Botrytis Blight
Botrytis blight, also know as gray mold, is a fungal disease caused by several species in the genus Botrytis. It affects the buds, flowers, leaves, and bulbs of many plants including: African violet, begonia, chrysanthemum, cyclamen, dahlia, geranium,...
- The Tomato Decoded: Holds More Genes Than Humans
The tomato has always been a complex fruit. Or is it a vegetable? Either way. Tomato, tomahto, right? The tomato, which is considered a fruit by botanists and a vegetable to the US government, has been demystified by a consortium of plant geneticists...
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