Master Gardener Laura Simpson answers your gardening questions.
Q. My pole beans all germinated and started growing nicely, but I noticed that the leaves are wrinkled and weird-looking. They are still growing, but they are not as lush as my other pole beans and don’t seem to have as many flowers. I don’t see any aphids. What could be causing this?
Leaf curl can be caused by several things. One of the first things to look for is the presence of aphids or other sucking insects. Since aphids will initially hide along tender growing tips and under leaves, early infestations can be tricky to find. Aphids reproduce quickly, so their presence will be obvious after about 20 minutes or so. (Just kidding – kind of!)
Water stress can also cause leaf curl in most plants. During a heat wave, this can happen quickly. Vigilance, supplemental watering, and a thick layer of organic mulch will help.
Nutrient deficiencies, especially nitrogen, phosphorus, and potassium (NPK), can cause leaf curl as well. Application of a dilute general-purpose fertilizer or compost tea will be helpful even in the absence of leaf curl. Take care not to over-fertilize vegetables since this can cause excessive leafy growth at the expense of flowering and fruiting.
If there are no aphids and you’ve been watering and fertilizing but still see leaf curl, your beans may have been affected by curly top virus (CTV). This virus can affect a wide range of crops, including tomatoes, peppers, beets, and other commonly grown vegetables. Sometimes you’ll only see symptoms on your bean plants and not on any other vegetables. If you suspect CTV, any affected plants should be pulled out and disposed of in the trash (do not compost). When planting next year, select varieties that are labeled resistant to CTV.
Beet leafhoppers spread CTV, so if you can discourage these insects from visiting your garden you can decrease the chances of infection. Leafhoppers like to hang out in weeds, particularly Russian thistle and mustard. Keep an eye out for these weeds and remove them promptly.
Q. How difficult are Alpine strawberries to grow? I had the opportunity to taste one and they are remarkable!
Alpine strawberries are not difficult to grow and are relatively easy to start from seed. There are several different types, including the traditional red and a white variety that tastes like pineapple. When starting from seed, use a sterile seed-starting mix and sow on the surface. Keep the starting mix moist, but not soggy, and the seeds should germinate within a week. Once the first set of true leaves appears they can be fertilized with extremely dilute fertilizer. I like to use water from my freshwater fish tank. Any over-fertilization will kill the seedlings.
Once the plants are large enough to transplant, find a sheltered spot that gets only a few hours of full sun per day. They really don’t like full sun in Southern California! The plants don’t produce runners but will survive several years if they are happy.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
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Riverside County
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San Bernardino County
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