Getting to the root of rot attacking crookneck squash

GARDEN Q&A

July 15, 2006|By JON TRAUNFELD AND ELLEN NIBALI | JON TRAUNFELD AND ELLEN NIBALI,SPECIAL TO THE SUN

Every year I have the same squash problem: Their crookneck yellows and the flower end rots off. I water once every two days.

Choanephora rot is a very common fungal disease (mostly of squash but pumpkins, eggplant and chili peppers are also susceptible). It first appears on dying blossoms still attached to fruits. The disease then spreads to the fruit. (Sometimes it first appears at the stem end.) Affected fruit parts turn dark brown to black, very fuzzy and mushy.

The pathogen likes warm, humid and rainy conditions. Its spores overwinter on dead plants and in soil and spreads to squash blossoms by bees, cucumber beetles and splashing water.

To control this rot, lay an organic mulch or newspaper covered with straw under plants. Avoid overhead watering. Remove infected fruits quickly and all plant residues at the end of the growing season.

Our new home has a mature 20-foot Korean Stewartia tree whose blossoms never fully open before dropping off the tree. The petals are curling at their edges. I don't know if this is normal or not. It gets morning and a bit of afternoon sun.

Stewartias are very choice trees. Margins of the white flowers naturally appear crimped, and the flowers open in early summer when few other trees or shrubs are blooming. Stewartias are also heralded for their highly decorative bark, red-to-purple fall color and freedom from pests and disease.

Your sun exposure is good. Stewartias do need acid soil. Sensitivity to drought and high temperatures on summer nights may account for the dropped blossoms.

Checklist

Early blight on tomatoes is appearing. This disease begins as small irregular spots with a bull's-eye pattern. Leaves turn yellow and fall off. Remove infected leaves early or spray with a gargen fungicide, such as copper or chlorothalonil.

To reduce mosquitoes in your yard, empty standing water from buckets, garden furniture, toys, tarps, gutters, etc. Clean up clutter or cover items to reduce water that mosquitoes need for breeding.

Jon Traunfeld, regional specialist, and Ellen Nibali, horticulture consultant, work at Maryland Cooperative Extension's Home and Garden Information Center, which offers Maryland residents free gardening information. Call the center's "hotline" at 800-342-2507 (Monday through Friday, 8 a.m.-1 p.m.) or e-mail plant and pest questions through the Send a Question feature at hgic.umd.edu.

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