![]() ![]() With Fusarium crown rot, the leaves often turn brown or black and eventually wilt. There are no chemical controls.įusarium wilt and Fusarium crown rot symptoms (Figure 7) begin as yellowing of older leaves. Mechanical transmission by workers touching plants and movement by aphid carriers can occur, but this is much less common in tomatoes than in cucurbits. The virus most often is carried in tomato seeds. Cucumber mosaic virus causes tomato plants to yellow and become bushy and stunted. If aphids become a problem, some applications of insecticidal soap are quite effective.Ĭucumber mosaic virus and herbicide injury are almost impossible to tell apart without previous knowledge of chemicals applied or laboratory confirmation. Damage usually is minimal on tomatoes and often can be ignored. Leaves appear shiny and are somewhat sticky when honeydew is present. Whiteflies and aphids (Figure 6) both cause leaf yellowing and leave a characteristic sticky excrement called honeydew. Characteristic symptoms are white or gray spots on leaves, surrounded by a black or brown margin. Septoria leaf spot is less common in Colorado than early blight. If the infestation is heavy, sulfur dust may help protect new leaves from infection. Space plants farther apart to improve air circulation. Do not plant tomatoes in the same place next year. Remove all diseased plant tissue on the ground, as the fungus overwinters on leaf debris. Affected leaves may turn yellow, then drop, leaving the fruit exposed to sunburn. If severe, the fungus also attacks stems and fruit. This disease produces brown to black, target-like spots on older leaves. Symptoms become prevalent during the hotter months. The caterpillars are susceptible to Bacillus thuringiensis (Bt), as well as to many common vegetable insecticides.Įarly blight ( Alternaria leaf spot) (Figure 5) is caused by the fungus Alternaria solani. They are voracious feeders, stripping leaves from stems and even eating unripe fruit. A green to reddish horn protrudes from the hind end. Tomato or tobacco hornworms (Figure 4) are large, green or gray-green caterpillars with white to tan v-shaped or dashed markings on their sides. Insecticides such as cabaryl or permethrin are effective controls, if needed. Wounded tissue may be more susceptible to diseases such as early blight. The adults chew small holes or pits in leaves. See Fact Sheet 5.540, Potato and Tomato Psyllids.įlea beetles (Figure 3) are small, black or brown beetles that jump when disturbed. For best control, dust the foliage, especially the undersides, with sulfur. They are sedentary while feeding and secrete small, white granules that resemble sugar. At first, they are yellow, then they turn green. To confirm psyllids, check the undersides of leaves for nymphs. Stems may become distorted, giving the bush a zig-zag appearance. They feed on tomato or potato plant sap and inject a toxic saliva that causes the characteristic “psyllid yellows.” Leaves turn yellow veins often turn purple. Psyllids (Figure 2) are more commonly found in eastern Colorado and are seldom a problem in western Colorado. Use row covers to protect tomato plants from the leafhopper. Hot, dry springs with predominantly southwest winds usually indicate increased problems with this disease. It is difficult to control because leafhoppers migrate from southern areas. Leaves and stems become stiff fruit ripens prematurely. Upper leaflets roll and develop a purplish color, especially along the veins. Infected plants turn yellow and stop growing. This problem is common in western Colorado but seldom found in eastern Colorado. Once soil temperatures rise, the problem usually corrects itself.Ĭurly top virus is transmitted by the beet leafhopper. Don’t plant tomatoes too early in the season. Phosphorus is abundant in our soils but may be unavailable to the plant when the soil is too cold. Phosphorus deficiencies (Figure 1) occur early in the growing season when soil is still cool. It is organized by affected plant parts: leaves, stems, roots and fruit. The key in Table 1 will help you narrow down the cause. To manage pests, identify the source of the problem by assessing the symptoms. Space plants for maximum air circulation.įailure to follow one or more of these steps can lead to pest problems.Keep the plant growing vigorously with proper water and nutrients.Improve garden soil by adding organic material such as compost.Good cultural practices can reduce or eliminate many problems.ĭespite the short growing season in many areas of Colorado, tomatoes are an easy and popular vegetable to grow.Assess the symptoms, then make the appropriate treatment.Tomato problems may be caused by nutrient deficiencies, diseases, fungi or insects.Tomatoes are an easy and popular vegetable to grow. ![]()
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