June is traditionally a month of crises in the garden, but it remains to be seen whether the worst is behind us or yet to come.
First, this spring has been the driest here in Weather Service history. Last month was the second-driest May (0.75 inches of rain) on record, exceeded only by the May 1939 rainfall of 0.41 inches. Secondly, June rain is generally a Washington question mark. Average June rainfall is 3.99 inches, but only twice in the last 10 years has the June rainfall met or exceeded that level.
Thirdly, a spring drought devastates plant life. Coming at a time when maximum growth is expected, it usually results in early-summer leaf drop on shrubs and trees. Plants that barely managed to survive the last winter probably will not make it through the next one -- and all plants will suffer.
Finally, lacebugs are infesting azaleas and spider mites most shrubs, thanks to the scorching heat in the final days of May. Even though the insect infestation moderated with cool temperatures earlier this week, look for major attacks next week when the hot weather returns. The next column will help you keep these pests from destroying your landscape. Meanwhile, here are some landscaping priorities for the moment: Forget trying to cultivate the weeds into control in the bedding garden. Mulch, mulch and mulch the weeds into oblivion, but cultivate first and then pour on the hardwood chips and such. If you've been tempted to apply sphagnum peat moss, don't; peat moss holds nine times its weight in water, and therefore has to be soaking wet before water drains out of the peat and finally gets to the soil and to your shrub or tree. We strongly encourage you not to use chemicals in the flower garden now because of the contact-killing nature of the herbicides; pre-emergent chemicals incorporating Treflan are fine, but they should be worked into the soil in late April or early May, not in June. Spot-treat weeds on the lawn with a plastic sprinkling can used only for weed control. Apply Balan or Dacthal now to control goose grass. Yellow nutsedge surfaced about two weeks ago, so spray with a minuscule solution of Daconate 6 (three eyedropper drops in 2 ounces of water in a hand sprayer). Nutsedge is the pale green narrow stalk that is taller than grass. Look for a second round of dandelion weeds where seeds from the first round fell in the past month. If you dig up dandelions with a weeding tool to a depth of only 5 inches, you'll stop more than 95 percent of them; if digging is out, water dandelions first, then spray lightly with any herbicide containing 2,4-D. On azaleas, the malformed white-gray growths clustered around some leaves are leaf galls, a disease usually triggered by excessive rainfall before blossoms unfold. Remove galls by carefully pinching them with your fingernails and throw them out. If left on the shrub, the galls will harden like stones. To prevent galls next year, spray with zineb or ferbam as leaf buds start to unfold. Blackened dogwood leaves are the work of aphids, the black coloring arising from the feces of aphids on the leaves. Usually, this black material is referred to as "sooty mold" because it attracts ants. Fetch your hose-end sprayer, add an ounce of water and two or three pinches of borax, and spray the leaves first thing in the morning. That ends that. On rhododendron, prune withered blossoms if you want flowers next year. Go down to the bare seed pods (called trusses) until they gather together in the stem. Continue down the stem until you come to the start of new growth on opposite sides of the stem; growth could be the size of a "pimple" or several inches long, depending on the vitality of the plant. The first time, use a serrated kitchen knife and cut through the stem a quarter-inch above the new growth. After a few cuts, you should be able to tackle things with your fingernails. Incidentally, lilac flowers of May should be pruned the same way, as should mountain laurel in the next few weeks. Fertilize rhododendron now with Hollytone, supplemented with a gallon of Miracid, MiracleGro or RapidGro water-soluble fertilizer. Repeat the liquid fertilizer between July 15-20 to encourage formation of dormant buds in late August-early September. Back on rhodies, the "sandwich" bites (also called "notches") on the leaves are the work of the black vine weevil. They eat leaves at night and hide in debris under the plant during the day; mating occurs in July and August when eggs are laid in the debris, after which the larvae burrow into the soil to spend the winter. In hardpan soil, the black vine weevil has a difficult time surviving the winter, but it has an easy time in the sandy soil of the Eastern Shore. Orthene (l 1/2 tablespoons per gallon), Thiodan (2 tablespoons) or Lindane (1 tablespoon) sprayed on the foliage and the debris or soil around the rhody will stop the problem; spray every three weeks from now to mid-August for total control. If your peony flowers have yet to open, you may be in luck. Quickly, erect three tall wooden stakes to surround the peony in a triangle, then tie the stalks around the stakes with soft cord; tie at 12-, 18- and 24-inch heights to lend strength to the stalks. When rain weighs down the flowers, the stalks won't collapse under the weight. Finger-pinch the stalks an inch or two below the flowers when they fade, and feed lightly with 5-10-5 scattered a few inches away from the stalks, scratched gently into the soil and watered. Scale is now starting to feed on the foliage of your shrubs after having wintered in protected shells. Any signs of gray-white deposits on woody trunk, branches or limbs is reason to commence spraying, especially on arborvitae, azalea, boxwood, cotoneaster, euonymus (guaranteed to have scale from one year to the next), juniper, ligustrum (privet), lilac and yucca. Three sprays spaced three weeks apart will do for all shrubs. Choose from liquid Cygon (4 teaspoons per gallon), Orthene (1 1/2 tablespoons) or Malathion (2 teaspoons); spray in the evening when the temperature has dropped below 80, otherwise you will burn the foliage. Dogwood borer season has reached the halfway mark, so check the bottoms of trunks (soil line up to 30 inches) for sawdust or fluid deposits. If you find either, use a kitchen wire ball to wipe fluid from the trunk to expose tiny borer entry holes. Insert a kitchen "cake testing" probe into the holes several times to clean out the fluid, then paint Thiodan (five eyedropper drops to 6 ounces of water) over the holes so the fluid is taken up; repeat the painting a few days later, then seal the holes with caulking material. If you were inundated with box-elder bugs last fall or this spring, consider attacking the problem at the source: the box-elder maple. Using a hose-end sprayer, apply liquid Diazinon, Malathion or Thiodan (best) to the leaves, limbs and trunk; apply when no rain is forecast and spray to the point of runoff. Spray now and repeat in early July to stop adults from laying eggs in mid- to late July.