Here are answers to some of the most common questions we receive about garden plants. You will find concise information on general gardening techniques as well as plant selection and care. For detailed information on specific plant pests and problems refer to our Common Garden Pests and Problems page.

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Horticulture Questions and Answers

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What are the most common problems of cucumbers and squash in this area?

Cucumbers, squash, zucchini and melons, collectively referred to as vine crops, are subject to a number of problems which include insects, mites, diseases and environmental factors.

A common problem is that vine crops flower but they do not set any fruit. If this occurs early in the season, the most likely reason is that the plant's female flowers have not yet begun to open. Since vine crops produce separate male and female flowers, it is imperative that both open at the same time for pollination to take place. Generally, male flowers start to open first followed by female flowers thereafter. Lack of proper pollination in the summer due to cold, rainy weather or a lack of insects for proper pollination can also result in a lack of fruit set.

Another common problem is misshapen or rotting fruit. Both commonly result from incomplete pollination or environmental stresses. Environmental stresses include fluctuations in soil moisture, rapid growth followed by extended dry weather, excess rain which kills roots or a salt build up in the soil. Maintaining more uniform soil moisture through the use of mulch can help reduce environmental stresses.

The most serious insect pests of vine crops include cucumber beetles, squash bugs and squash vine borer. Cucumber beetles are 3/8 to 1/2 inch long and may be either spotted or striped. They feed mainly on the foliage and flowers and can completely devour small plants. Their greatest damage, however, results from transmission of bacterial wilt, a lethal disease which results in wilting and death of the plant. Control of these beetles is critical to preventing the disease. Another common insect is squash bugs which feed on leaves causing then to wilt and turn brown and crisp. Small populations of squash bugs can be tolerated as they do not transmit disease. Many insecticidal dusts registered for use on vegetables will control cucumber beetles and squash bugs. Check the label. Varieties resistant to squash bugs and bacterial wilt are also available.

During hot, dry weather spider mites can cause considerable damage to vine crops. Spider mites are very small, about the size of grains of pepper. They suck plant juices which results in dull, stippled foliage. Fine webbing is usually also present. Although pesticides can be used to help control spider mite populations, a forceful steam of water can be used to regularly wash the mites off the foliage before populations build up to damaging levels.

For information on squash vine borer listen to message "Squash Vine Borer."

In addition to bacterial wilt already discussed, vine crops are attacked by powdery mildew, mosaic and several leaf spots. Powdery mildew results in a white powdery growth on leaf surfaces. It is most common in hot, humid weather. Mild infections can be tolerated but a severe infection can kill the plant. Fungicidal sprays applied early will control the disease. Resistant varieties are available.

Several leaf spot diseases affect vine crops. Mild infections can be tolerated but severe infections require diagnosis by a professional to determine if they are fungal or bacterial in origin.

Finally, a virus disease, mosaic, affects many vine crops. The disease results in a mottling of the foliage and a stunting of the plant. No chemical controls are available. Remove diseased plants immediately. Control insect pests, especially aphids, which can transmit the disease.

As a general rule, leaf spot diseases can be lessened or prevented by avoiding overhead watering, growing plants in well-drained soils, keeping weeds down and destroying plant debris to avoid overwintering these problems.