What herbicide to use for purple nutsedge in corn, peanut and soybean fields

Purple nutsedge, also known as Cyperus rotundus, dry three-edge, thunder god's head, etc., is a perennial herbaceous plant. During its growing period, it can rapidly reproduce and grow in a short time at a rate several times or even dozens of times, quickly occupying the ground, and has an extremely strong ability to compete with crops for fertilizer and water. So what herbicide should be used for purple nutsedge?

Introduction to purple nutsedge

Purple nutsedge, called “Xiangfu” in traditional Chinese medicine, is the dried rhizome of the Cyperaceae plant Cyperus rotundus; its main effects are to soothe the liver and relieve depression, regulate qi and ease the middle, and regulate and relieve pain.

But in the fields, farmers also call it three-edge grass, thunder god's head, pointed hair grass, etc. It is a perennial herbaceous plant. Its underground corms produce rhizomes, which then grow new corms, which sprout young grass, one plant after another, growing continuously. During its growing period, it can rapidly reproduce and grow in a short time at a rate several times or even dozens of times, quickly occupying the ground, and has an extremely strong ability to compete with crops for fertilizer and water. Therefore, in the eyes of farmers, it is one of the malignant weeds.

Morphological characteristics of purple nutsedge

Purple nutsedge, also known as Cyperus rotundus, dry three-edge, thunder god's head, etc., is a perennial herbaceous plant that prefers wet and cool conditions. Its underground corms produce rhizomes, the rhizomes grow new corms, and the new corms sprout young grass, one plant after another, growing continuously. The leaves are linear, as long as the culm, about 6 mm wide, with leaf sheaths. The flowers are unisexual and monoecious. The inflorescence is usually 10-15 cm, with 3-10 spikelets. The male spikelets are terminal, and the female spikelets are lateral. The heading stage is in summer and autumn. During its growing period, it can rapidly reproduce and grow in a short time at a rate several times or even dozens of times, quickly occupying the ground, and has an extremely strong ability to compete with crops for fertilizer and water.

Habitat, harm and distribution of purple nutsedge

Purple nutsedge is a weed in autumn-ripening dry crop fields. It prefers loose soil and occurs rather seriously in sandy soil. It often occurs in large numbers during the seedling stage of autumn-ripening dry crops such as cotton, soybean and sweet potato, seriously affecting the early growth and development of crops. It is also a major weed in orchards, mulberry and tea gardens, but it is most harmful in cotton-growing areas. It often forms single small communities or mixes with other plants, competing with them for light, water and fertilizer, causing poor growth of other plants. It is also a host of insects such as the white-backed planthopper, black stink bug and hispid beetle, and is one of the malignant weeds with relatively great harm worldwide. Its distribution covers almost all parts of the country. Because purple nutsedge reproduces by underground stems, manual weeding or general herbicides can only kill the aboveground part, and its underground tubers can sprout at any time within a week to continue causing harm, so it is extremely difficult to control.

Control methods for several crops

1. Corn

Because amide herbicides before seedling emergence and nicosulfuron herbicides after seedling emergence in corn fields have been used alone in large quantities for many years, certain weeds have been artificially selected to grow, and some previously uncommon broadleaf weeds and sedges have become increasingly stronger. Purple nutsedge keeps appearing in corn fields in various places, seriously affecting agricultural production.

After purple nutsedge appears in corn fields, use chemicals for timely control. MCPA-sodium, bentazone, carfentrazone-ethyl, flucetosulfuron and other chemicals can be used for control, and spraying should be done at the 4-5 leaf stage of corn, which has the least impact on corn.

2. Soybean and peanut

The control methods for purple nutsedge in soybean and peanut fields are basically the same. Bentazone and fomesafen can be used for spraying control at the 1-3 compound leaf stage of soybean seedlings for the best effect. For severe purple nutsedge in soybean fields, glyphosate can be sprayed 7 days before harvest, which can control purple nutsedge and also promote soybean defoliation and early maturity, facilitating mechanical harvesting. When controlling purple nutsedge in peanut fields, acifluorfen or fluoroglycofen combined with bentazone can be used for a better control effect.

3. Cotton

In recent years, with the widespread application of new plastic film cotton planting technology, especially the promotion and application of ultra-wide film drip irrigation under film cotton planting technology, a suitable ecological environment has been created for the reproduction of purple nutsedge, causing the spread and diffusion of purple nutsedge in cotton fields to become increasingly serious. Trifloxysulfuron-sodium can be used for control when cotton is about 25 cm tall, but during the vigorous growth period of cotton, purple nutsedge mainly reproduces by tubers, and the weed density is high, and spraying herbicides is not possible. Glyphosate can be prepared into a medicinal solution, and a brush can be used manually to apply it to the stems and leaves of adult purple nutsedge plants, so that it is absorbed and transmitted to rot the underground tubers and make them extinct.