Ron Jujawski | Garden Journal: Be on the lookout for lily leaf beetles
Among the most attractive flowers in the summer garden are the lilies, including Turk's cap lilies, tiger lilies, Asiatic and Oriental lilies. Yes, I know it is still spring, but I mention these plants now because there is a critter, besides me, who has a serious interest in lilies. It is the lily leaf beetle. However, our interests are at odds with one another. I like lilies for their large showy flowers; lily leaf beetle likes lilies for lunch.
The first indication that lily leaf beetles have chosen your lilies as a favored dining spot is the presence of holes in the leaves. If you see that, search out quarter-inch long, shiny red-bodied beetles with black heads, legs and undersides. During daylight hours, the shade-loving beetles may be tucked deep into leaf clusters or on the undersides of the leaves. Interestingly, the beetles squeak when gently squeezed, but why anyone would want to squeeze a beetle is beyond me.
At this time of year, the adult beetles are not only feeding, but are also laying their eggs on the undersides of lily leaves. The soft, orange, brown or yellowish larvae that hatch from the eggs are slug-like in appearance. Their role in life seems to be to eat as much of a gardener's lilies as possible. However, their toilet habits leave a lot to be desired as they pile their own excrement on their backs. I assume they do this to keep predators from using them as a meal, not to mention that it also deters gardeners from hand-picking the pests from lily leaves. After three weeks of their repulsive habits, the larvae drop to the soil, where they pupate and eventually emerge as adults. The adults will then feed on lilies throughout the rest of the growing season.
To manage this critter, hand-pick the adults and crush the eggs on the underside of lily leaves. Weekly applications of a product containing Neem, a botanical insecticide, will kill very young larvae and repel adult lily leaf beetles. Products containing spinosad, a microbial insecticide, may also be effective.
By the way, lily leaf beetles do not attack day lilies. Try attacking these tasks:
- Make the first sowings of sweet corn and bean seeds this week. Additional sowings may be made at two-week intervals. Alternatively, sow early, mid-season and late varieties of corn. With green beans, plant a short row each time. Otherwise, your family will suffer from green bean overload at dinner time. Late-season plantings can be larger if you're planning to can or freeze green beans for winter consumption.
- Plant seedlings of leeks at the edge of the vegetable garden, where they won't be disturbed during garden clean-up operations in autumn. Leeks can remain in the garden and be harvested as needed well into autumn, and with a deep cover of straw or chopped leaves placed over the plants just before the ground freezes, they can be harvested well into winter.
- Be alert for flea beetles on early planted vegetables, especially radishes and cole crops, i.e. cabbage and relatives. These tiny black beetles hop like fleas when disturbed and can be very destructive to seedlings. Applications of organic insecticides, e.g. pyrethrum or spinosad, to plant foliage provide some control. As with any pesticide, organic or otherwise, always read and follow label instructions.
- Avoid applications of insecticides to fruit trees, blueberries and raspberries when these plants are in bloom. Insecticides not only make the pollinating bees upset, they also make them dead.
- Scratch some 5-10-5 or similar fertilizer into the soil around spring flowering bulbs while they are still in bloom. This will help them build up energy for next year's blooms.
- Have soil tested for pH if the bloom of lilacs was sparse. Acidic soil is a frequent cause for poor flowering on lilacs which prefer a pH of 6.4 or higher. Late summer pruning and overgrown plantings are also factors causing reduced bloom.
- Pot up recently received bare-root perennials if you can't plant them in the garden within a day or two of arrival. Alternatively, they'll keep in the refrigerator, but only for about a week, assuming no one will confuse them as salad makings.
- Thin out some of the young shoots of border phlox and delphinium by snipping or pinching them off at the base. This thinning process will improve their appearance while also helping prevent infection by powdery mildew.
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