What are the sunflower planting techniques and disease control methods?

Sunflowers are not only beautiful flowers, but also have edible value; the seeds can be used to make oil, and the economic benefits of planting them are very high. So what are the sunflower planting techniques? How should diseases be prevented and controlled?

1. What are the sunflower planting techniques?

1. Site selection and land preparation

Choosing a good plot when planting is an important factor in increasing yield and boosting returns. Sunflowers are widely adaptable to soil and can adapt to everything from heavy clay to light sandy soil. They also have a certain tolerance to acidity and alkalinity, generally with a pH between 5.5-8.5; greater acidity or alkalinity will have a certain effect on their growth. Choose a site with deep soil and a level terrain, and a crop rotation period of more than 3—4 years is also required. During land preparation, prepare the land finely, plow the soil deeply, break up the soil, remove stones and other hard objects, and then apply sufficient base fertilizer.

2. Seed selection and treatment

When selecting, be sure to choose varieties with excellent quality, fast growth, high yield, and strong stress resistance and disease resistance. When selecting seeds, keep seeds that are plump and consistent in shape, size, and color, and discard those of poorer quality. Before sowing, the seeds must first be treated to increase the germination rate. First place the selected seeds in the sun to bake for 2-3 days, and remember to turn them in time while sunning. Then use 150 ml of 40% zinc phoxim, mixed with 5—7.5 kg of water, to soak the seeds, eliminating pathogens on the seed surface and preventing disease occurrence.

3. Sowing

The sowing time depends on the local climate and soil. Generally, the sowing time is between April and May. Sowing methods can include hole sowing and furrow drilling, generally with hole sowing as the main method. Generally, the holes are 5-6 cm deep, the sowing rate is about 1-1.5 kg per mu, and 4-5 seeds are sown per hole. Use wide and narrow row sowing, with a large row spacing of 1 m, a small row spacing of 60 cm, and a plant spacing of 60 cm. After emergence, thin and fill in seedlings in time according to the actual emergence situation. Keeping about 1,400 plants per mu is optimal.

4. Later field management

Later field management mainly includes intertillage and weeding, fertilizer and water management, and supplemental pollination. Carry out intertillage and weeding 2-3 times each year to ensure strong growth. The first can be done together with thinning seedlings, with intertillage 3-4 cm deep, and apply an appropriate amount of urea as topdressing. The second is one week later, with deep intertillage 8-10 cm. The third is at the disk-forming stage, with deep intertillage 3-4 cm, and apply topdressing fertilizer. Artificial supplemental pollination of sunflowers is extremely important. It is a cross-pollinated crop, and artificial pollination can increase the seed-setting rate, increase yield, and improve returns. The specific method is: wear gloves, and 2-3 days after flowering, touch them one by one by hand. Artificial supplemental pollination is best done in the morning or evening, avoiding the high-temperature period at noon.

2. Sunflower disease control methods

1. Sclerotinia rot

Sunflower sclerotinia rot is caused by the pathogen Sclerotinia sclerotiorum, and mostly occurs during periods of low temperature and heavy 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 lesions. In humid environments, white mycelium and brown sclerotia appear at the lesions. In severe cases, the plants wilt and wither, and the diseased tissue decays and breaks easily, with black sclerotia inside.

Control methods: The main cause of sclerotinia rot is that the pathogen overwinters dormant in the soil, diseased residues, and seeds. When the temperature rises 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: deeply plow and disinfect the soil, burn diseased residues in a centralized manner, disinfect and sterilize seeds to reduce pathogens, and apply more phosphorus and potassium fertilizer during planting to increase plant disease resistance. When the disease occurs, spray treatments such as thiophanate-methyl and procymidone wettable powder.

2. Verticillium wilt

Verticillium wilt mainly harms adult sunflower plants and mostly occurs in low-lying land and when planting density is high. When the disease occurs, the leaf tips begin to lose green, then the entire leaf loses green, 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.

Control methods: Similar to sclerotinia rot, the pathogen also overwinters in the soil, diseased residues, and seeds, and after sowing invades through wounds or young roots. The preventive measures are the same as for sclerotinia rot. If diseased plants are found, remove them from the field in time and burn them, disinfect the diseased holes, and when necessary, drench the roots with a 400-fold dilution of 20% carboxin emulsifiable concentrate, which gives 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 reductions in sunflowers. The leaves, petioles, stems, and flower disks can all be infected. When the disease occurs, a small number of spore pustules appear at the affected sites. As the disease develops, after the spores rupture, brown powder appears, leading to black powder in the later stage, and ultimately causing the plants to die.

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, apply more phosphorus and potassium fertilizer to increase disease resistance, and when the disease occurs, remove diseased plants from the field and burn them, and spray 15% triadimefon wettable powder at 1000-1500 times dilution or 50% carboxin emulsifiable concentrate at 800 times dilution for control.