Major Strawberry Fruit Rot Risk Expected May 15, 2018
Beginning May 15, in the early afternoon in Western NC and late evening in Eastern NC, the strawberry decision support tool is predicting high-risk conditions that favor both Anthracnose Fruit Rot (AFR) and Botrytis Fruit Rot (BFR) pressure for several days.
In the mountains, there has been no (modeled) risk of disease for more than 12 days and in the east the last risk period was around May 7 (for BFR). Therefore, rowers are advised to implement management steps within the next 24-36 hours if no products have been applied in the last 5-7 days. The pages that support the strawberry decision support tool also have links to the most up-to-date recommendations to manage BFR and AFR with regard to the best products and best rotation programs.
About 90% of BFR infections occur through the flower and it takes 24-30 days for the flower to develop into a harvestable berry. Therefore, the decision to spray for BFR depends on the predicted conditions this week PLUS the expected length of harvest. If harvest will end early June, then this predicted time of risk is not concerning. (Note: infected berries are likely to show symptoms during this coming week of wet conditions but they were most likely infected 26 days ago).
If growers have not observed anthracnose to date, then the risk of AFR is very low. We have experienced high pressure in our research plots the last two weeks (in plots not sprayed). We also experienced a very low volume of samples in the Plant Disease Clinic with anthracnose problems. Therefore, AFR risk is low in most fields. However, the risk of AFR cannot be guaranteed to be zero and the conditions this week are highly favorable for disease spread.