Types of Garden Enemies
Control. Use resistant plants where possible. The University of California has a list of moderately resistant ornamental shrubs. Treat soil where plants have died of the disease with carbon bisulfide, and wait 60 days before replanting.

A similar mushroom root rot (Clitocybe tabescens) is important in the decline of citrus trees in Florida. It also is responsible for ill-health of about 200 ornamentals, with Australian pine very susceptible.

TEXAS ROOT ROT (Phymatotrichum omnivorum)
is the most destructive plant enemy in parts of the Southwest, attacking and often killing more than 1700 kinds of plants, with an annual loss of a hundred million dollars in Texas alone and about half that in adjacent states. The rot occurs from July to frost, killing plants in circular spots ranging from a few yards to an acre in diameter. The ground is covered with yellow to buff mats of mycelium and white cottony spore mats. Dark-brown or black rhizomorphs carry the fungus through the soil to other roots.

Control. Replace diseased plants with resistant varieties, which include most of the cotyledons. Ammonium sulfate will sometimes save a valuable ornamental tree. Make a ridge of soil around the tree at the end of the branch spread; work 1 pound ammonium sulfate into the soil for each 10 square feet of surface and fill the basin with water; repeat in 5 to 10 days.

SOFT ROT (Erwinia carotovora).
This is a vile-smelling, gooey disease of iris, often following borer injury, and of yellow calla lilies. It is also a vegetable rot, more common on stored root crops than those in the field. The bacteria enter through wounds, and in warm, wet weather the rot is very rapid, rhizomes or fleshy roots becoming soft and pulpy with a most offensive odor. In iris the interior of a rhizome may disintegrate into a soft yellow mess while the epidermis remains firm. Tips of leaves are withered, basal portions shredded.

Control. Keep iris in full sun, uncrowded, and with upper part of rhizomes exposed to the sun. When it is the year to divide iris, do it as soon as possible after flowering, cutting away all portions with any trace of rot and disinfecting rhizomes and leaf fans, after they have been cut back to 6 inches, in a pail of bichloride of mercury (2 tablets to a quart of water) for 20 to 30 minutes. Let the plants dry in the sun a day or two before replanting.

STEM ROT (Sclerotinia sclerotiorum).
This is another sclerotial disease, but here the sclerotia are large, about the size of peas, black, and formed loosely in the pith of peony or other stems, or in sunflower heads, or in a cottony weft of mycelium on vegetables affected with a watery rot.




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