Latin name: Botrytis cinerea
Reason for Concern:
1) Under the right environmental and field conditions (wet weather during fruit development and poor circulation in the canopy) it can cause yield losses.
2) Can remain dormant and disease symptoms do not show up until after the fruit has been harvested.
3) Losses are most severe in wet weather throughout harvest.
In dry conditions, infected fruit flowers brown and shrivel. Under moist conditions, grey tufts of fungus form on blighted blossoms and on mature fruit. Fruit can appear healthy at harvest but develop rot soon after.
Botrytis is a common fungus that cannot be eliminated from fields, only reduced. Same causal agent as blossom blight and cane botrytis; the fungus overwinters on weeds, in dead leaves, mummified fruit and canes as black fungal bodies. In spring, under humid conditions, the spores infect new and mature growth via water or wind or direct contact with already infected plant parts, resulting in primocane infections through petioles. All flower parts except sepals are very susceptible. Infected new canes wilt and die. Dead canes may be covered with grey mold.
- During bloom, Botrytis will cause shriveling and browning of flowers
- As fruit begins to form, look for soft/rotting fruit with grey tufts of fungal spores, especially after extended wet periods and in areas of heavy foliage.
- During harvest, Botrytis will occur naturally as fruit over ripens and begins to decay, so look predominantly at developing/ripening fruit for symptoms as this will be more indicative of whether or not there is a concern for Botrytis in that field. However, overripe fruit can be a source of contamination in new fruit, keeping a field clean and well picked is important to minimizing this risk.
- In early spring, examine canes for whitish/light brownish lesions on new primocanes and floricanes.
- Botrytis cane blight isn’t often a large concern in blackberries, however, in seasons of extremely favorable conditions (long periods of wet cool weather), there is potential for cane damage and decreased yield. This is why it is particularly important to monitor for Cane Botrytis in early spring.
| Cultural Controls:
- Minimize or adjust irrigation so plants are not wet for long periods.
- Use drip/trickle irrigation.
- Cane vigor control and primocane suppression.
- North-South row orientation promotes even sun exposure and good air movement through plants.
- Planting resistant cultivars may be an option in some situations.
- Harvest fruit at correct stage of maturity; do not allow it to overripen.
- Shorten harvest intervals, if possible. Don't let overripe fruit remain in the field.
- Move harvested fruit to cold storage as soon as possible.
For information about chemical controls, check with our Pesticide Guide.