|
Disease |
Crops |
Weather |
Rotation years out |
Seedborne |
Resistant |
Control by |
Other |
| Alternaria leafspot (Alternaria spp) |
Cole |
Cool, wet |
many |
yes |
- |
yes |
- |
| Angular leafspot (Pseudomonas lachrymans) |
Curcubits |
70-80 |
1-2 |
yes |
yes |
yes |
Stay out of wet fields |
| Anthracnose (colletotrichum lagenarium) |
Curcubits |
Warm, wet |
>2 |
- |
yes |
yes |
Rotation and resistant cultivars may be inadequate in fall |
| Anthracnose (colletotrichum piperatum) |
Pepper |
Warm, wet |
- |
yes |
- |
yes |
Fruit storage at 45-50 degrees F slows disease development |
| Anthracnose (colletotrichum spp.) |
Tomato |
- |
>2 |
- |
- |
- |
- |
| Bacterial canker (Cornebacterium michiganense) |
Tomato |
- |
>5 |
yes |
yes |
yes |
Survives up to 2 years in compost. Sterilize pruning tools. Avoid contaminated irrigation water, succulent plant growth & sandy soil |
| Bacterial leafspot (Xanthomonas campestris pv. vesicatoria) |
Pepper, |
Warm |
>3 |
yes |
no |
yes |
Bacteria can overwinter if buried >12". Windbreaks of tall grasses every 12 rows decrease spread |
| Bacterial speck (Pseudomonas syringae pv. tomato) |
Tomato |
Cool, wet |
>3 |
yes |
no |
yes |
In Calif., it is usually not economical to treat if infection first occurs after the 5-leaf stage (little injury after that point) |
| Bacterial wilt (Pseudomonanas solanacearum) |
Solanaceae, |
85-90 degrees F |
no |
yes |
tolerant |
- |
Compost may lessen. Avoid fields with nematodes |
| Belly rot (Rhizoctonia solani) |
Cucumber |
Wet, hot |
- |
- |
no |
- |
Fruit can be protected by mulches |
| Blackleg (Leptosphaeria maculens) |
Cole crops |
Wet, cool |
>4 |
yes |
- |
- |
Use new containers. Avoid dipping plants in water. Can infect in storage |
| Blackleg (Erwinia carotovora) |
Potato, carrot, beet, cucumber, bean |
- |
>3 |
yes |
no |
- |
Spread by seed corn maggots and infected cutting knives. Slow early growth promotes disease |
| Black rot (Xanthomonas campestris pv. campestris) |
Cole crops |
warm, humid |
>3 |
yes |
yes |
- |
Use new containers. Avoid topping transplants |
| Clubroot (Plasmodiophora brassicae) |
Cole crops |
- |
7-10 |
- |
yes |
no |
pH >7.2 will control. Solarization with low level fumigation can control |
| Common blight (Xanthomonas phaseoli) |
Beans |
warm, wet |
2-3 |
yes |
no |
yes |
- |
| Downey mildew (Peronospora parasitica) |
Cole crops |
Wet, 50-60 degrees F |
>2 |
no |
yes |
yes |
- |
| Downey mildew (Pseudoperonospora cubensis) |
Curcubits |
Cool, wet |
no |
no |
no |
no |
Overwinters in tropical areas. Isolate from infected fields. Botanical controls exist |
| Early blight (alternaria solani) |
Solanaceae |
Warm, wet |
- |
yes |
few |
yes |
Provide good air drainage. Trellis tomatoes |
| Choanephora fruit decay |
Curcubits |
Wet |
- |
- |
- |
- |
Provide good air circulation |
| Fusarium wilt (Fusarium oxysporum f. niveum) |
Tomato, curcubits |
Warm termperatures |
10-12 |
yes |
yes |
no |
Solarization and soil pH near 7 helps control. Avoid fields with nematodes |
| Fusarium yellows (Fusarium oxysporum f. conglutinans) |
Cole crops |
Soil temperature above 70 degrees F |
- |
no |
yes |
no |
- |
| Gray mold (Botrytis cinerea) |
Tomato |
Cool, wet |
- |
no |
yes |
no |
Provide good drainage. Raise pH to 6.3 or greater. Keep N levels high |
| Gummy stem blight (Didymella bryoniae) |
Curcubits, sorghum, rice |
Warm, wet |
>2 |
no |
no |
yes |
Extra potash at fruit formation can decrease severity |
| Late blight (Phytophthora infestans) |
Potato, tomato |
Cool nights (55-76 degrees F) with high humidity |
- |
yes |
yes |
- |
Isolate tomato from potato fields. Kill potato foliage 10-14 days before harvest |
| Phomopsis rot (Phomopsis vexans) |
Eggplant |
Warm |
3 |
yes |
yes |
yes |
- |
| Powdery mildew (Erysiphe cruciferarum) |
Cole crops, curcubits |
Dry August followed by cool wet September |
no |
no |
yes |
no |
Transported north by wind. Sulfur-based fungicides effective but can cause crop damage |
| Pythium fruit rot |
Curcubits |
High humidity |
- |
no |
- |
yes |
Increase air circulation. Do not apply excessive N. Avoid standing water |
| Scab of cucumber (Cladosporium cucumerinum) |
Cucurbits |
High humidity, cool, wet nights |
yes |
no |
yes |
yes |
Improve air and soil drainage |
| Scab of potato (Streptomyces scabies) |
Potato |
Inadequate soil moisture, dry, warm |
yes |
yes |
yes |
- |
Maintain soil pH of 5.0-5.3. Spread by contaminated manure |
| Sclerotinia |
Many |
Humidity, temperatures 50-76 degrees F |
yes |
no |
no |
yes |
Resistant crops include beets, onion, spinach, peanut, corn, grasses. Flooding for 23-45 days lowers incidence |
| Scurf (Monilochaetes infuscans) |
Sweetpotatoes |
- |
3-4 |
yes |
no |
yes |
Use scurf-free seed roots with fungicide treatment. Bed in disease-free soil. Cut transplants 1" above soil line. Dip infected slips in fungicide |
| Southern stem blight |
Most |
Warm, especially following dry spell |
long |
no |
no |
yes |
Avoid light sandy soils. Use solarization, deep plowing, good weed control |
| Stem anthracnose (Colletotrichum truncatum) |
Lima bean |
- |
3 |
yes |
no |
yes |
Well drained soil helps lessen severity |
| Streptomyces soil rot |
Sweetpotato |
Hot, dry |
no |
- |
yes |
- |
Avoid light sandy soils. A pH under 5.2, drip irrigation and organic matter decrease severity |