When should I plant Chinese cabbage? 

Chinese cabbage performs best when planted in summer for a fall crop.  (Chinese cabbage frequently goes to seed when planted in spring.)  Sow the seed of Chinese cabbage at a depth of 1/4 to 1/2 inch in July.  Rows should be spaced 2 feet apart.  Thin plants when 1 to 2 inches tall.  After thinning, plants should be spaced 12 to 18 inches apart within the row.  Suggested varieties for Iowa include ‘Jade Pagoda,’ ‘Greenwich,’ and ‘Michihili.’ 

Chinese cabbage is a versatile garden vegetable.  It has a sweeter, milder flavor than true cabbage.  The crisp, tender leaves may be used like lettuce in salads, shredded for cole slaw, steamed or stir-fried. 

I have wort-like growths on the undersides of my grape leaves.  What is it and does it need to be controlled? 

The wort-like growths on the grape leaves were probably caused by the grape phylloxera.  The grape phylloxera is a small, aphid-like insect.  The grape phylloxera has a complex life cycle that affects the leaves and roots of the grapevine. 

The foliar form survives the winter as eggs under the bark of the grapevine.  The eggs hatch in spring and the young insects (nymphs) move to the new leaves.  They feed on the upper surfaces of the leaves, causing galls to form on the lower leaf surfaces.  Mature phylloxera females lay eggs within the galls.  Subsequent generations of nymphs emerge, crawl to the shoot tips, settle on new leaves, and form new galls.  Fortunately, leaf-infesting phylloxera do not cause serious harm to healthy grapevines.  Control measures are not necessary. 

Root-infesting phylloxera overwinter as nymphs on the roots.  They mature in spring and produce eggs that hatch into subsequent generations of nymphs, which start new galls on roots.  Winged adults develop in late summer or early fall and emerge from the soil to lay eggs on the grapevine stems.  The root form of the grape phylloxera will destroy heavily infested plants.  Fortunately, the grape varieties grown in Iowa are not damaged by the root form. 

When should I harvest my summer squash? 

Harvest zucchini and other long-fruited summer squash varieties when they are 1½ to 2 inches in diameter and 6 to 8 inches long.  Scalloped types are best when 3 to 5 inches in diameter.  Fruit should have soft skins (rinds) that are easy to puncture with a fingernail.  Seeds should be soft and edible.  Harvest plants frequently for continuous production. 

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