Diseases and control methods of hollyhock

Hollyhock Diseases: Rust

symptom

The pathogen is sheath rust, and perennial hollyhock plants are very susceptible to hollyhock rust.

After being infected with rust, chlorotic spots appear on the front of the leaves, and round, brown, powdery spore piles can be seen on the back.

When the disease is serious in the later stage, the leaves gradually turn yellow, wither, and fall off, and the whole plant becomes weak.

Prevention and treatment methods

Spraying Bordeaux liquid on the plants in spring or summer, or disinfecting the seeds before sowing can have a preventive effect.

In the early stage of the disease, you can spray 1000 times diluted 15% triadimefon wettable powder, or 1000 to 1500 times diluted 70% thiophanate-methyl wettable powder, or 600 times diluted 75% thiophanate-methyl wettable powder, etc. Spray once every 7 to 10 days, and spray 2 to 3 times in a row, all of which have good prevention and control effects.

Hollyhock Diseases: White Spot Disease

symptom

Hollyhock white spot disease is also called leaf spot disease, which mainly harms the leaves of hollyhock.

In the early stage of the disease, small brown spots will appear on the surface of hollyhock leaves. As the disease progresses, the spots gradually expand into circles or ovals. The center of the spots is grayish white and the outer edges are reddish brown.

When the humidity of the surrounding environment reaches a certain level, a gray-brown mold layer will appear on the lesions.

Prevention and treatment methods

Increase the application of phosphorus and potassium fertilizers to hollyhock, control the amount of nitrogen fertilizer used, apply less or not at all.

In the early stage of the disease, you can use 800 times diluted 75% thiophanate-methyl wettable granules, 500 times diluted 50% carbendazim wettable granules, or 1200 times diluted 70% thiophanate-methyl wettable granules to spray for prevention and control, once every 10 days. Spraying 3-4 times in a row can effectively control the disease.

If you find diseased plants, remove the diseased leaves in time, pay attention to the density of branches and stems, keep the plants ventilated and light-permeable, and minimize the possibility of disease.