How to control alligator weed? A detailed guide to practical methods
Alligator weed, also known as water spinach, hollow amaranth, revolutionary grass, water peanut and so on, is a perennial herbaceous plant of the genus Alternanthera in the amaranth family. It is native to Brazil and was introduced in China to Beijing, Jiangsu, Zhejiang, Jiangxi, Hunan and Fujian, later escaping to become wild. As an extremely harmful invasive species, it has been listed among China's first batch of invasive alien species. Let's take a look below at the control methods for alligator weed!
Harmful characteristics
The main harmful effects of alligator weed are blocking waterways and affecting water traffic. It crowds out other plants, making community species uniform. It covers the water surface, affecting fish growth and fishing. It harms crops in farmland, reducing yields. It reproduces in large quantities in field ditches, affecting farmland drainage and irrigation. It invades wetlands and lawns, damaging the landscape. It breeds mosquitoes and flies, harming human health.
Agricultural measures
Usually strengthen field management; do not farm carelessly but cultivate intensively and carefully. During the seedling stage of alligator weed, repeatedly and meticulously pull it out and clear it, dig out the remaining stem nodes in the soil cleanly, and gather them to dry in the sun and burn. Areas where alligator weed has not been found should strengthen precautions to prevent its asexual propagules from invading fields, pastures or waters. In areas where it has already occurred, measures should be taken to control its spread.
Biological control
When the minimum temperature in early spring rises back above 10°C, release adult alligator weed flea beetles (Agasicles hygrophila), releasing 1000-3000 adults per hectare of water area, which can control its harm and spread. However, using the host-specific natural enemy insect Agasicles hygrophila, native to South America, to control aquatic-type plants gives better results, but the effect on terrestrial-type plants is poor.
Physical control
Adopt manual and mechanical removal and salvaging. When removing and salvaging alligator weed, dig as deep as possible or salvage it together with the roots. The removed and salvaged alligator weed can be gathered and burned or fully composted and rotted into green manure for use. In addition, when the effect of chemical control is not ideal, part of the alligator weed can first be salvaged and removed to reduce the population density of alligator weed, and then the herbicide can be sprayed.
Chemical control
1. Starane: Starane is a herbicide for controlling broadleaf weeds. It not only has a killing effect on the root system of alligator weed, but also removes the above-ground stems and leaves of alligator weed quickly, thereby achieving a long-lasting weed control effect. To control alligator weed on rice field ridges, use a 1000-fold dilution of 20% Starane emulsifiable concentrate and spray it directly at the basal leaves. Adding a small amount of laundry detergent to the Starane emulsifiable concentrate can increase the control effect by about 20%. When used in farmland, if broadleaf crops have already sprouted and emerged, Starane must not be used, otherwise it will cause phytotoxicity.
2. Roundup aqueous solution: 4 Roundup aqueous solution can control alligator weed along river channels, ponds and ditches. Adopt a high-concentration, low-water-volume application method, using a 100-fold dilution of 41% Roundup aqueous solution for spraying, so that the liquid adheres to the stems and leaves of alligator weed. Roundup aqueous solution entering the water will not cause water pollution and is non-toxic to fish, shrimp and so on. In seriously affected fish ponds, application should be divided by area to prevent large numbers of alligator weed from dying and rotting, which would cause oxygen deficiency in the fish pond.