Disease: Damping- Off
Crops Affected: Garden Pea, Fava Beans and Lettuce
Description: The rotting/decaying of seeds in the soil due to overly wet conditions. If the seedling manages to emerge it will be affected with the either the fungi pythium, fusarium or rhizoctonia.
Identification: Lack of seed emergence is a good clue the seeds are being affected. If the seedling becomes infected with the fungi upon emergence it will appear weak in the stem, can become blackened and will topple over and die at any point.
Threat Severity: In Burnaby the threat could be fairly severe with really wet shoulder seasons. However, the crop can be planted in late spring after severe wet conditions pass or the seeds can be started inside to avoid the conditions. The threat would be increased if the responsible fungi are present in the soil of the area - I am not sure about my site, but all my seeds did well in the soil this year.
Best Practices for Mitigation:
- Plant seeds in optimal conditions. Damp soil but not soaked and no heavy rains during seed germination time.
- Crop rotation.
- Seed indoors and transplant at the appropriate time. This way the moisture can be better controlled and you can choose to use a sterilized soil if your area is particularly wet with risk of presence of the dampening off fungi.
- Fungicide treated seeds are an option on conventional sites. For ecological sites like mine, there are a couple of options of this nature: Priming, pelleting, hot water treatment, plant and oil extracts, bleach disinfectant or biological seed treatment.
Testing Available for Disease in Seed?: I believe testing for fusarium is available. Not a bad idea to have seeds tested every once in a while or buy the initial seed from a trusted source that does have vigorous seed testing protocols.
Disease: Bacterial Blight
Crops Affected: Garden Pea and Fava Beans
Description: A bacterial infection of the leaves. The bacteria can overwinter in crop residue or in seeds and spread easily in favourable conditions (warm, wet and humid).
Identification: Starts as shiny green spots and increases in size, yellow discolouration may happen around the spot. Dead leaves will remain on the plant and pods may show dark red-brown lesions.
Threat Severity: Blight is quite a severe disease that should be avoided on the farm. It can live for many years and transfer between many plants.
Best Practices for Mitigation:
- Crop rotation.
- Infected plant residue removed from the farm completely.
- Don't allow leaves to wet for extended periods of time.
- Manage mulch and crop residue well.
Testing Available for Disease in Seed?: Yes. Tested and disease free seed is available.
Disease: Fungal Blight
Crops Affected: Garden Pea
Description: Very similar to bacterial blight in appearance but caused by fungi not bacteria.
Identification: Irregularly shaped purple or brown splotches on the leaves. Black lesions on the stem.
Threat Severity: Just as severe as bacterial blight and is a big problem if any level of infection becomes apparent on the farm. Fungal blight can survive for years and transfer between plants very easily.
Best Practices for Mitigation:
- Same as bacterial blight. Most diseases thrive in wet, humid and warm conditions. So, try to always keep plant foliage dry and ensure good air circulation between plants and leaves.
Testing Available for Disease in Seed?: Yes. Tested and disease free seed is available.
Disease: Powdery Mildew
Crops Affected: Lettuce, Fava Beans and Garden Pea
Description: Common group of fungi that are host specific. Many types of powdery mildew with many types of hosts. It does not need as wet of conditions as other fungal diseases so it is quite a bit more prominent in many regions.
Identification: Powered residue appearing of leaf foliage.
Threat Severity: Mildly severe. It usually happens in the later part of the season when the crop is mostly mature. The vegetables can often still be marketed at full size. However, if a severe infection the yield and fruit quality can be reduced. Powdery mildew is more of a threat in seed crops since they need more maturation and drying time on the plant.
Best Practices for Mitigation:
- Crop rotation.
- Good cultural practices.
- Sufficient spacing for air circulation.
- Plant in full sun and avoid shade if possible.
- Topical spray for small infection sites. Use cider vinegar and water solution or use baking soda and water solution to spray.
Testing Available for Disease in Seed?: No... Powdery mildew is a systemic disease and cannot be transferred to other parts of the plant.
Disease: Botrytis Rot
Crops Affected: Lettuce, Fava Beans and Garden Pea
Description: Leaves near ground can turn light brown and host grey-brown fuzzy growth of spores.
Identification: Lower leaves yellow and eventually the whole head starts to die. Watery brown decay develops on the underside of the head
Threat Severity: Pretty severe. Botrytis can live in crop residues, soil and seed stock for years.
Best Practices for Mitigation:
- Crop rotation.
- Good cultural practices.
- Sufficient spacing for air circulation.
- Keep surface of plant beds dry by digging in drip irrigation to just water the roots.
- Can plant in raised beds.
- Plant in full sun and avoid shade if possible.
- Topical spray for small infection sites. Use cider vinegar and water solution or use baking soda and water solution to spray.
Testing Available for Disease in Seed?: Yes. Tested and disease free seed is available.
Fun Fact about Botrytis: Dessert wine is typically made from grapes that are infected with botrytis as it makes the grapes extra sweet! Not harmful to consume.
