Types of Garden Enemies
Fig. 21
They are prevalent in the South and are primarily cotton pests but also attack legumes, egg- plant, and some other vegetables, citrus, pecan, and sunflower. Some stink bugs act as vectors of plant disease, distributing the organisms causing yeast spot of lima bean, kernel spot of pecan.

CANKERS AND DIEBACK
A canker is a localized lesion or diseased area, usually on a woody structure. In its definitely limited character a canker is comparable to a leaf spot on foliage, but a canker may continue to enlarge until it girdles a cane, stem, or tree trunk, killing the water-conducting tissues and causing a dying back from the tip. Some diseases known under other names have a canker as part of the symptom picture, like that formed on a limb after a branch has died from fire blight. Some diseases commonly called cankers, like boxwood canker, are more properly blights.

BROWN CANKER OF ROSE (Cryptosporella umbrind).
This is one of the more important rose diseases. Very small purplish spots on the canes acquire white centers and reddish-purple margins, there being numerous spots on a single cane. During the winter, especially on parts of a cane kept moist with a mulch, the spots grow together into large cankers, sometimes several inches long, with tan centers, purple or red borders, and little yellow tendrils of spores protruding in wet weather. If the cankers expand around the cane to girdle it, there is subsequent dieback.

Control. Cut out infected canes at spring pruning. Avoid leaves, manure, and other moist mulches over winter. If a copper spray is used weekly for black spot control, brown canker will automatically be taken care of. I almost never have a case of brown canker in gardens regularly treated with the ammoniacal copper in Tri-ogen.

COMMON, or STEM, CANKER OF ROSE (Leptosphaeria coniothyrium).
This is an indefinite canker, smudgy from the dark fungus spores massed under the cane epidermis. The fungus is a weak parasite and enters through pruning or other wounds; it cannot penetrate unbroken healthy tissue. A frequent means of entrance is through long stubs left in pruning or in cutting roses through the season, for the rose stem usually dies back to the node, that is, bud or leaf axil. Frost cracks provide another common means of entry.

Control. Always cut a rose stem just above a leaf or bud; never leave more than 1/4 inch of stub, less if possible. Avoid feeding and watering late in the season; this encourages succulent tissue ready to split at the first drop in temperature.




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