After a few frosts, and more cold weather on the way, the growing season is rapidly coming to a close. Harvest has been on-going for several weeks now, and in some areas is starting to wrap up. For many, wrapping up harvest is a sign of the end of the season, however, there are still some important disease management steps to consider before we button everything up for the winter and look ahead to pruning (more on this in my next article).
In vineyards and orchards alike, a consistent challenge that producers face is limiting the amount of overwintering disease inoculum. As part of an integrated disease management program, it is important that effort is put forth in reducing the amount of overwintering inoculum that could result in consistent or increased disease pressure in orchards and vineyards.
Fungi and bacteria, which are two of the most impactful organisms that cause plant diseases, in some cases are able to over winter in the soil or on infected plant debris. Some diseases do not over winter in our area of the country, but fore the ones that do, they are largely unaffected by the severity of the winter.
Fungi are able to overwinter in dormant stages via survival structures such as sclerotia. These sclerotia are dark in color, thick walled and nearly impossible to eliminate once they are in the soil. Due to the fact that diseases are likely to overwinter, regardless of the severity of the winter, it is imperative that we utilize sanitation practices to prevent or reduce the presence of the pathogen. Reducing or removing the presence of a pathogen takes away a key component of the disease triangle. Any action taken to remove a component of the disease triangle and disturb the cycle of the pathogen can result in less severe infection or failure of the disease to develop.
A step that can be taken to reduce challenges, especially as they relate to diseased fruit and plant debris is removal of these materials. Although time consuming, removing mummy fruit, leaves, vines, branches, or any other diseased plant material from the production area can significantly reduce the amount of disease inoculum present. Ideally, these materials would be burned or removed from the farm in some fashion, so as not to allow continuation of the diseases present on those materials.
Too, applying urea (46-0-0) at a rate of 40 lb./acre can help speed up leaf decomposition, which in turn reduces the disease inoculum for diseases such as apple scab. This application will add additional nitrogen to your soil, so please consider this as you evaluate your nutrient programs.
Given an opportunity to integrate these cultural measures into your disease management program, its important too that growers are aware of fungicides that can be used as tools in their programs. Relying solely on fungicides without putting efforts into cultural control measures will result in a low return on investment of the fungicide product and application costs.
Now is a great time of year to evaluate your disease management decisions and think about what worked well, what didn’t work well and consider what changes can be made for next season. Its important to be patient with this process as well. Given a few years of intensive cultural control measures, you can greatly reduce the risk of disease that would typically over winter in your orchards and vineyards.
Frank Becker is the Agriculture and Natural Resources Extension Educator with Ohio State University Extension – Wayne County, and a Certified Crop Adviser, and may be reached at 330-264-8722 or becker.5872osu.edu
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