Types of Garden Enemies
Control. We have long searched for a good soil disinfectant which will kill crown rot sclerotia without harming living plants. We do not have it, but it is possible to kill mycelium and temporarily prevent spread of disease with bichloride of mercury. Use a 1 to 1000 dilution, 2 tablets to a quart of water, and pour it into the hole after you have dug out the rotted plant and all surrounding soil, making sure you don't drop any of the sclerotia back into the space as you dig. Also pour your solution over crowns of surrounding plants-it will not injure them-but don't rely too much on this treatment. There are sure to be some sclerotia left behind not killed by the bichloride, and you are more than likely to have the disease again in the same spot next year. If you have fallow soil, without living plants, you can kill most sclerotia with chloropicrin.

There are many wood rots of trees recognized by the type of sporophores, fungus fruiting bodies in the form of shelves or brackets, on tree trunks. But by the time such sporophores appear, the rot has gotten beyond control. The wise thing to do is to prevent entrance of the heart rot fungi in the first place. Make smooth pruning cuts flush with the main trunk; jagged stubs are ideal entranceways. Be sure to make an undercut on a limb first and then a second a few inches from the main trunk before the third and final cut. This prevents the weight of the limb from tearing a strip down the trunk. Clean up trees as soon as possible after ice storms and hurricanes. Paint cut surfaces with tree paint.

There are many root rots flourishing on plants in low, poorly drained locations. Only three rather special types can be discussed here. A mushroom root rot (Armillaria mellea) is damaging to fruit and nut crops, to ornamental trees and shrubs on the West Coast, and occurs occasionally elsewhere. Sheets of fan-shaped mycelium are formed between bark and wood at the root crown, and clumps of honey-colored toadstools appear at base of dead or dying trees Black cordlike rhizomorphs, "shoestrings," grow out through the soil and carry the disease from infected to healthy roots. Trees and shrubs planted on lands recently cleared of oaks suffer most from this rot. Also susceptible are ornamentals planted in valleys where flood waters deposit extra soil around the crown, or trees covered too deep in grading operations and kept too wet by artificial watering.

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