Rainfall has been highly variable in the ginseng growing area, with some areas getting very dry and others having experienced heavy rains from thunderstorms. Other than some heat stress issues from the heat earlier this month, the crop is progressing normally with no unusual issues reported.
Except for those fields that had flooding and high Phytophthora pressures, if you have high disease pressures at this time of year, you may need to consider one of two possibilities:
- You are not getting good coverage of all plant surfaces. This is a good time to recalibrate your sprayers and/or replace nozzles. For a refresher on sprayer considerations for ginseng and proper sprayer setup and calibration, consult “How to Spray Ginseng” and “How to Set up a Crop Sprayer” on Sprayers101.
- You may be dealing with resistance of the pathogen to one or more of the fungicides in your rotation. Resistance is the ability of a fungus to withstand a pesticide spray that was once able to control it. It builds up over time when a pest is repeatedly exposed to the same active ingredient or group, and individuals with mutations that allow them to survive a spray multiply and gradually (or sometimes rapidly) take over the population. See below for resistance management strategies.
