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Disease of the Month - Entomosporium Leaf and Berry Spot | |
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| Causal Organism: Entomosporium mespili
Crops Affected: Saskatoon berries
Disease Cycle:
- High humidity / precipitation and warm temperatures
- Spore dispersal is triggered by precipitation
- Flourishes from early-May through mid-July
- Optimal temperatures for development are 20-26°C
- Affects leaves of succulent new shoots and berries (immature to mature)
- May overwinter on fallen leaves & twigs (not proven conclusively)
- May also be present on twigs and branches
Symptoms:
- Most serious disease of Saskatoon berry
- Infected fruit is downgraded or becomes unmarketable
- Infection of greater than 6% of fruit surface area is considered unusable by processors
Leaf Symptoms
- Small, angular brown spots
- Spots may grow & join together, with a yellow halo
- Leaves may turn yellow & may fall off if petioles are infected
- Severe defoliation can reduce productivity
Fruit Symptoms
- Watery, greyish lesions
- Fruit may become discoloured, disfigured, shrivelled or cracked
- Fruit stalks may become infected
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Entomosporium lesions - varying degrees - mild to severe |
Blocky, angular lesions - low to medium levels of infection | Yellowing leaves + lesions | Severe infection |
Photos by Robert Spencer |
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Severe Entomosporium infection resulting in cracking and desiccation of fruit | | |
Photo by Robert Spencer | | |
Management:
- Ensure adequate air circulation
- Pruning
- Orchard orientation
- Careful consideration of plant stand density
- Control weeds
- Apply water to the soil surface (not sprinkler applications)
- Apply preventative fungicide sprays
- Fungicide Spray Timing
- Flowering stages = White Tip, Petal Drop, Green Fruit (varies with product)
- Make 1st application after first rain event that occurs 1+ days after flowering (when petals open up)
- Connected to spore dispersal
- Fungicide Selection
- Chemistry/efficacy of products varies somewhat
- Remember the Pre-Harvest Interval (PHI) as this sets limits on application timing
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For more information about the content of this document, contact Robert Spencer.
This information published to the web on March 26, 2018.
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