What are the common pests and diseases of sunflowers? A detailed explanation of prevention and control methods

Sunflower is an important cash crop in our country and is grown across a very wide area. However, as its planting area continues to expand, its pest and disease damage is also becoming more and more serious, severely affecting the yield and quality of sunflowers and causing economic losses for growers. So which pests and diseases harm sunflower yield and quality? Let's take a look together with Qinnongwang.

1. Sclerotinia rot

Sunflower sclerotinia rot is caused by the pathogen Sclerotinia sclerotiorum, and it mostly occurs during periods of low temperature and frequent rain in spring. When the disease occurs, brown lesions appear on the stems or leaves of sunflowers. As the disease develops, the brown lesions gradually spread to other parts, and finally concentric rings form at the lesion sites. In humid environments, white mycelium and brown sclerotia appear at the lesions. When the disease is severe, the plants wilt and wither, and the diseased tissue becomes decayed and breaks easily, with black sclerotia inside.

Prevention and control methods: The main cause of sclerotinia rot is that the pathogen lurks in the soil, diseased residues, and seeds to overwinter. When temperatures rise the following year, it begins to multiply in large numbers, spreads by wind, and finally infects sunflowers. Therefore, these measures should be taken at planting time: deep plow and disinfect the soil, burn diseased residues in a centralized manner, disinfect and sterilize seeds to reduce the pathogen, increase the application of phosphorus and potassium fertilizers when planting to increase plant disease resistance, and when the disease occurs, spray treatments such as thiophanate-methyl and procymidone wettable powder.

2. Verticillium wilt

Verticillium wilt mainly harms mature sunflower plants, and it mostly occurs in low-lying land and when planting density is high. When the disease occurs, the leaf tips begin to lose green color, then the entire leaf loses green color, and the areas between the veins turn yellow and then brown. As the disease develops, the leaves of severely affected plants gradually dry up and die. In environments with air humidity, white mold-like substances appear on the leaf surface.

Prevention and control methods: Similar to sclerotinia rot, the pathogen also overwinters in the soil, diseased residues, and seeds, and after sowing it invades through wounds or young roots. The preventive measures are the same as for sclerotinia rot. Diseased plants should be promptly removed from the field and burned, and the diseased holes should be disinfected. When necessary, drench the roots with a 400-fold dilution of 20% carboxin emulsifiable concentrate, which has good results.

3. Rust

Rust is a fungal disease to which sunflowers are susceptible. During an epidemic of this disease, it can cause severe yield reduction in sunflowers. Leaves, petioles, stems, and flower discs can all be infected. When the disease occurs, a small number of spore piles appear at the affected sites. As the disease develops, brown powder appears after the spores rupture, later leading to black powder, and ultimately causing the plants to wither and die.

Prevention and control methods: The pathogen likewise overwinters or oversummers in the soil, diseased residues, and seeds, so the preventive measures are similar to the previous two. Choose varieties with strong disease resistance for planting, strengthen management during planting, and increase the application of phosphorus and potassium fertilizers to increase disease resistance. When the disease occurs, remove diseased plants from the field and burn them, and spray a 1000-1500 fold dilution of 15% triadimefon wettable powder or an 800-fold dilution of 50% carboxin emulsifiable concentrate for control.

4. Downy mildew

Downy mildew can occur in both seedlings and mature plants, and it is prone to occur under low temperature and high humidity, when soil moisture is high, or in continuous cropping land. When the disease occurs, the leaves begin to lose green color, and white downy mold layers appear on the undersides of the leaves, causing slow growth and dwarfing of the plants. As the disease develops, the chlorotic area expands and the white downy mold layers spread. In the later stages of the disease, the leaves turn brown and withered, and the plants lose their sun-facing ability, often leading to abnormal seed setting or empty stalks.

Prevention and control methods: Downy mildew is mainly caused by the pathogen lurking in seeds. After sowing, as temperatures rise, the pathogen begins to multiply and infect. Be sure to implement crop rotation when planting, choose varieties with strong disease resistance, and plant at a reasonable density. If individual diseased plants are found, promptly pull them out and take them out of the field to burn. For large-scale outbreaks, spray a 1000-fold dilution of 58% metalaxyl-mancozeb wettable powder or an 800-fold dilution of 64% Sandofan M8 wettable powder for control.

The above are the prevention and control methods for common sunflower pests and diseases brought to you by Qinnongwang. The content on sunflower pests and diseases is introduced here. If you want to learn more, please stay tuned to Qinnongwang.