Types of Garden Enemies
Aluminum sulfate has been used for acidifying soil but may cause some plant injury. Sulfur is safer and can be combined half and half with ferrous (iron) sulfate for treating the soil around shrubs, using 1 to 1% pounds per 100 square feet. For a quicker response foliage can be sprayed with iron sulfate, using 1 ounce in 2 gallons of water, adding 1/4 ounce soybean flour to increase adhesiveness. Dr. Pirone in Modern Gardening also suggests using iron ammonium citrate, the "green pearls" employed in photographic processing, at rate of 1 ounce to 5 gallons of water.

Very new is the use of an iron-chelate complex in the soil to correct iron deficiency without changing soil acidity. One chelating agent, ethylene diamine tetra-acetic acid, is marketed under the trade names of Versene and Sequestrene.

Once every 17 years the PERIODICAL CICADA, 17-year locust (Magicicada septendecim) has its day. And what a day it is! The air is hideous with its continuous high-pitched whine, and oak trees look as if they had been suddenly struck by blight, being covered with twigs and small branches

Fig. 24

The true 17-year locust ranges from Massachusetts to Georgia and west to Wisconsin and Texas, but there is a 13-year form from Virginia to Oklahoma and south to the Gulf of Mexico. Eggs are laid in twigs and small branches, the position marked by protruding splinters. When they hatch in 6 or 7 weeks, the larvae drop to the ground and feed on tree roots for the next 13 or 17 years, though seldom causing appreciable damage. Then they crawl out of the ground, leaving holes or perhaps a small chimney 1/2 inch across, and climb up a tree trunk where the hard nymph skin splits down the back to free the adult cicada. The dark, wedge-shaped body is about an inch long with wings extending well beyond it. Eyes, legs, and wing veins are reddish orange. In the flight year trees are covered with empty skins by the thousand, for as many as 20,000 nymphs have spent their long existence under a single large tree. The shrill noise is made by the males, with two drumlike membranes on the sides of the first abdominal segment. It can be simply horrible; you feel you must leave home to get away from it; motorists coming suddenly into a cicada region stop their cars and look at the motor, sure that something has gone wrong. It lasts about a month, and then all is peace.

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