With all the rain lately, gardeners have had to plant later than usual. It is not surprise that with later planting and all the humidity in the air that disease and pest problems begin to rise. Have no fear because the Extension office is here.
One of the big problems that have cropped up around the state has been Powdery Mildew. For those who have not heard of powdery mildew it is a disease that occurs on the above ground parts (especially the leaves) of many deciduous trees and shrubs, as well as herbaceous ornamental plants, indoor house plants and many agricultural crops. Some signs to look out for that your crop may have it are to look at the upper and sometimes lower surfaces of the leaves and stems of suspected plants; they will have a white powdery appearance. Powdery mildew is caused by several closely related fungi that survive in plant debris or on infected plants. The fungus is very host specific meaning that no two powdery mildew are the same. If you do see powdery mildew on one plant and there are the right conditions such as the high humidity that we have been seeing then there is a likely hood of it effecting several plants.
Most of the time powdery mildew only affects the look of the plant but in the case of roses it can start to cause leaves to fall off. There are fungicides out there such as dinocap, trforine, or sulfur that can help rid your plant of powdery mildew. Otherwise a combination of baking soda (1 1/2 tablespoons) and light weight horticultural oil (3 tablespoons) in water (1 gallon) has been shown to be effective for powdery mildew control. With any control it needs to be applied every seven to 14 days from bud break until humid weather subsides. It is important if you are going to use a fungicide that you read the label and follow the instructions. Try pre-testing it on your plants before applying it to all of them.
To avoid powdery mildew try finding plant varieties that are resistant to the disease. It won’t be a guarantee of the plants getting the disease but it will help to prevent sever cases from happening. Watch how much you are watering and try spacing the plants further apart this will help increase air flow. Remove and destroy any infected plant debris, this will help prevent the spread to next year’s plants.
All the information above is from the UW-Extension Cooperative Extension Wisconsin Horticulture website. They have information on a lot of different diseases and pests in the area. The Lincoln County UW-Extension office just recently created a website for home and commercial gardeners to take a look at problems that have come up in their area, as well as provide information that may be helpful for improving on their gardens. The website is called Lincoln County Horticulture Hotline. The following is the web address you can type in to go directly there: http://fyi.uwex.edu/lincolncohort/. If you find that you are having issues with pests and diseases feel free to call the Lincoln county extension office and they will work on helping to solve the problem. The number for the office is 715-539-1072.