Derz-The Polyphagous Pest of Agriculture Ecosystems

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Cutworms (Agrotisspp) are the larvae of several species of night-flying moths belonging to family Noctuidae. They are serious polyphagia pests of different crops and attack a wide range of plant species in their various growth stages. They are generally considered to be notorious agricultural and garden pests worldwide. Cutworm complex, Agrotisipsilon, is one of the most widely distributed species and causes considerable damage in hilly and sub-mountainous regions of Jammu and Kashmir. Here in Kashmir it is commonly called as Derz. These are voracious leaf, bud and stem feeders and can destroy entire plants. They get their name from their habit of “cutting” off a seedling at ground level by chewing through the stem. 

Young caterpillars feed on leaves and later on stems. Mature caterpillars cause the most damage. They are capable of eating or destroying the entire plant. They girdle and cut-off young seedlings at ground level during the night, dragging them into a tunnel in the soil and feed on them during the day. Cutworms are more frequent in the soil with plenty of decaying organic material or where organic manure has been applied. Research on the practical application of assessment methods used in monitoring the cutworm had resulted in the growing population size of cutworm in farms, gardens and even in the lawns of the official summer residence of Governor of Jammu and Kashmir where supervisory staff of Floriculture department often after planting flower seedlings find them damaged the next morning. An officer of Floriculture department who is in charge of Raj Bhawan Lawns and Cheshmashahi recalls how this problem is a nightmare. He says that they plant hybrid flowering seedlings blooming with life the evening before and see them tore down by cutworms next morning.

The problem aggravates as female moths can lay hundreds of eggs, separately or in small clusters. They typically deposit them on low-growing plants and on plant residue. Young larvae feed on the foliage or small roots of weeds or crops until they reach about 1/2 inch in length.  Emerging or newly emerged weeds can be very attractive sites for egg laying and feeding by small larvae. At this stage, they can begin feeding on seedling stems, either cutting through them or burrowing into them. Corn, peppers, tomatoes, beans, and the crucifer family are common hosts, but they will attack any kind of herbaceous plants. Cutworm larvae grow as large as two inches long. They may go through as many as three generations per year. Cutworm abundance and development is greatly affected by weather, especially rainfall.  April and May weather patterns are the first key to potential black cutworm problems. Moths mate and lay eggs from early spring (black cutworm) to late summer/winter (dingy, glassy, and bronzed cutworm). 

Several options exist for the grower who wants to manage cutworms. As cut worms can’t be seen during the day, most gardeners don’t know they have a cutworm problem until they see the evidence in the morning after a night of feasting has occurred. In order to manage the cutworm, digging the soil and wet foliage to about 2 inches deep exposes caterpillars to predators and to desiccation by the sun. Fields should be prepared and vegetation and weeds destroyed ten to fourteen days before planting the crop in the field. If the field is planted soon after land preparation, some cutworms may be alive and attack the new crop. Delaying transplanting slightly until the stems are too wide for the cutworm to encircle and/or too hard to cut may reduce cutworm damage. Flooding of the field for a few days before sowing or transplanting can help kill cutworm caterpillars in the soil. By applying Bacillus thuringiensis in your garden, cutworms can be controlled as this bacteriumis known to kill cutworms and is widely available in garden supply stores. It is the natural way to get rid of cutworms without causing harm to plants or animals.You can control cutworms by placing aluminium foil or cardboard collars around transplants.  This creates a barrier that physically prevents cutworm larvae from feeding on plants.  When placing these collars around plants, make sure one end is pushed a few inches into the soil and the other end extends several inches above ground.  This should prevent most species of cutworms from getting to your plants.Cutworms love to eat cornmeal, but it hurts their digestive system, many will over eat it to the point of killing themselves. The use of granular soil insecticides and broadcasting or banding liquids has met with mixed success. Different insecticides of Acetylcholine esterase inhibitors, Organophosphates and Neonicotinoids are effective against this pest. However, the pesticide should be sprayed in the afternoon for best results against cutworms since they feed after dark.

 

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