Diseases and Pests of Purple-backed Arrowroot and Their Control

Diseases of Purple-backed Arrowroot

Sclerotium rolfsii

Purple-backed arrowroot often suffers from white rot. When white rot occurs, the stems or leaves of the purple-backed arrowroot will turn brown and rot, and white silky mycelium will grow, causing the above-ground parts to wither and die. The disease is more serious in July and August, and the pathogen is Sclerotinia microphylla. The disease is prone to occur when the soil is too wet, poor and lacks fertilizer.

Prevention and control methods: When white rot occurs on purple-backed arrowroot, add 70% pentachloronitrobenzene to disinfect the soil and remove the diseased soil. During cultivation, pay attention to ventilation to prevent over-dense planting.

Leaf spot

Leaf spot mainly harms leaves, but can also harm leaf sheaths. In the early stages of the disease, there are small spots on the leaves, which then become larger. The disease can occur throughout the year. During the peak period of the disease, a large number of leaves can dry up, causing serious damage.

Prevention and control methods: apply more base fertilizer, enhance disease resistance, and remove diseased leaves in time. Spray 500-600 times diluted 75% thiophanate-methyl wettable powder for prevention and control before the disease occurs.

Pests of Purple-backed Arrowroot

Scale insects

Scale insects are mainly mealybugs, which suck plant sap with their piercing-sucking mouthparts. In mild cases, the leaves turn yellow and age, affecting plant growth. In severe cases, leaves fall off and the entire plant dies. However, since adult scale insects have a waxy outer shell, it is difficult for general pesticides to penetrate. Once an infestation occurs, prevention and control is difficult.

Prevention and control methods: Scale insects can be killed more easily by spraying pesticides during the peak nymph stage. Spray once every 7-10 days, and spray 2-3 times continuously. For prevention and control, you can use 1000 times diluted 40% oxydemeton-methyl, 1000 times diluted 50% DDT, or 3000 times diluted 2.5% cypermethrin for spraying.

Red Spider

Red spider mites are a common harm to plants. They use their sharp mouth needles to absorb nutrients from leaves, affecting the normal growth and development of plants. In a high temperature and dry environment, red spiders and other insects reproduce rapidly and cause serious damage.

Prevention and control methods: Keep the environment ventilated and humid, and spray water on the back of the leaves frequently to control the reproduction of red spider mites. Since pesticides are difficult to kill insect eggs, control is generally carried out during the adult and nymph stages after the eggs hatch. They can be sprayed with 1000 times diluted 20% trichlorodicofol emulsifiable concentrate or 1000 times diluted 40% oxydemeton-methyl emulsifiable concentrate.