Helen Vanella, Master Gardeners of Greene County
| Special to the News-Leader
Something is wrong with my cucumbers, leaves are fuzzy-looking with white spots and also yellow spots that turn brown. What is the cause and what can I do about this?
This is most likely due to powdery mildew, a very common fungal disease in cucumbers and other garden crops, especially in late summer. This may first show yellow spots which then turn to a white, powdery appearing coating on the leaves. Since this can reduce yields and weaken, even kill, the plants, it is important to get this controlled as much as possible. Managing this disease will require both preventative practices, as well as treatment when necessary. The biggest factor in development of any fungal disease is humidity and poor air circulation. Good prevention will involve watering early in the morning to allow the leaves to dry out more quickly. Watering at the base of the plant is also good, keeping the leaves drier. Spacing of the plants is also important to provide better air circulation between the vines. It is also helpful to look for varieties which are more disease resistant. Treatment can involve a simple homemade spray of one gallon water with one tablespoon of baking soda. Some home recipes also involve white vinegar or a diluted soap solution. For a particularly severe infection may require use of commercial fungicide but be sure to follow label instructions closely.
Another possibility in addition to the powdery mildew could be bacterial wilt carried by cucumber beetles. I would recommend monitoring the vines closely for these pests and keep them under control, if possible, as there is no cure for bacterial wilt.
My cucumber vines are starting out with male flowers. Is there some special fertilizer I can use to encourage formation of female flowers?
There is no fertilizer that will produce female flowers faster. What you need is “tincture of time,” otherwise known as patience! Cucumbers of the gynoecious type produce both male and female flowers, with the male flowers appearing a few days before the female flowers are produced. Female flowers can be identified by a tiny cucumber shape at the base of the flower, which is not found in male flowers.
I have pulled my potato plants, plan to put in root crops such as carrots, beets and radishes next. What prep and soil additives are needed?
Since potatoes are such heavy feeders, using large amounts of potassium and phosphorous, I would consider doing a soil test before adding too many additional nutrients. The soil should be loosened completely and lots of organic matter such as compost, well-rotted manure, and the like should be worked in before planting the root crops. A soil test would help determine exactly what nutrients are needed and how much should be added. In the future, you might consider crop rotation, perhaps 3-4 years, with potatoes followed by a type of legume. Rotation of crops will help even out the nutritional requirements of various crops and help prevent development of certain diseases.
Readers can pose questions or get more information by calling 417-874-2963 and talking to one of the trained volunteers staffing the Master Gardener Hotline at the University of Missouri Extension Center in Greene County located inside the Botanical Center, 2400 S. Scenic Ave., Springfield, MO 65807.
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