What are the main diseases of spinach? What are the control methods?

Spinach is a vegetable with rather obvious seasonality, but later, with advances in cultivation techniques and the development of varieties, it can basically be grown in all four seasons. Spinach has high nutritional value and can supplement iron. So during cultivation, what are the main diseases? What are the control methods?

I. What are the main diseases of spinach?

1. Spinach downy mildew

Spinach downy mildew is a fungal disease caused by an oomycete. The pathogen overwinters as mycelium on diseased leaves and seeds, or as oospores in diseased dead leaves. The mold layer on the underside of the lesion consists of the pathogen's sporangiophores and sporangia; the sporangia spread via airflow and produce new lesions. Dew formation and high humidity are important conditions for infection by the pathogen. Spinach downy mildew mainly damages the leaves. The disease is severe under conditions of high planting density, poor field ventilation, low-lying waterlogged areas, and low temperature with high humidity.

2. Spinach white spot disease

Spinach white spot disease is a fungal disease. The pathogen overwinters in the soil as mycelium along with diseased plant residues, and the following spring it spreads via wind and rain. It is prone to occur under weak growth vigor and warm, humid conditions.

The symptoms of spinach white spot disease mainly appear on the leaves. The lower leaves are affected first; the lesions are small and round with distinct edges, yellowish-white in the center and brown to purplish-brown on the outer edge, gradually developing into white spots after expansion. When humidity is high, grayish hairy matter can be seen on some lesions; when dry and wet conditions alternate sharply, the center of the lesion tends to crack. The pathogen mainly spreads via wind and rain. It is prone to occur under weak growth vigor and warm, humid conditions, and is severe in low-lying, poorly ventilated areas with poor management.

3. Spinach gray mold

It mainly damages the leaves. Initially, light brown irregular spots appear, which then expand into pale brown, moist, large lesions, and gray mold develops on the lesions on the underside of the leaves, namely the pathogen's conidiophores and conidia. Severely affected leaves turn blackish-brown and rot; under dry conditions they lose water and turn black, with many gray moldy substances visible.

II. What are the control methods for the main diseases of spinach?

1. Control methods for spinach downy mildew

(1) To control spinach downy mildew, note: choose disease-resistant varieties, carry out reasonable crop rotation, plant at a reasonable density, and increase the application of phosphorus and potassium fertilizers. Also use carbendazim and fenaminosulf for soil treatment, improve the seed germination rate, sow at the appropriate time, and plant at a reasonable density.

(2) During the seedling stage, note reasonable irrigation and topdressing, keep the nitrogen, phosphorus, and potassium ratio reasonably balanced, and timely spray foliar fertilizer to promote robust plant growth, improve disease resistance, and make the leaves thick, the leaf color fresh and tender, and the natural flavor rich.

(3) Chemical control: in the early stage of the disease, spray with 50% Miekete wettable powder 800 times solution or 50% Anke wettable powder 2500-3000 times solution, once every 7-10 days, for 2-3 consecutive sprays. Reduce the spread of downy mildew. For treating downy mildew, use 58% Lusujing wettable powder 500 times solution, or 60% Keluba 500 times solution, or 72% cymoxanil-mancozeb 600 times solution. Alternate them, once every 7-10 days, for 2-3 consecutive sprays.

2. Control methods for spinach white spot disease

(1) Strengthen management and improve the disease resistance of the plants;

(2) After harvest, promptly remove diseased plant residues and bury them deeply or burn them in a centralized manner to reduce the source of the disease;

(3) In the early stage of the disease, spray 75% Shengke chlorothalonil wettable powder 500 times solution, or 50% carbendazim 800 times solution for control.

3. Control methods for spinach gray mold

(1) Choose moisture-tolerant varieties such as spinach.

(2) Strengthen field management and avoid the occurrence of low-temperature and high-humidity conditions. Low temperature not only weakens the vitality of the plants; when low temperature lasts a long time, the plants remain in a half-dead state for a long period, with weak resistance, and are very susceptible to gray mold when high temperature occurs. Therefore, doing everything possible to raise the temperature in the field or greenhouse and reduce humidity is the fundamental measure for controlling this disease. (3) After the spinach harvest, promptly remove diseased plant residues and burn them in a centralized manner or bury them deeply.

(4) Irrigate and fertilize reasonably, and drain promptly after rain to prevent the occurrence of disease conditions.

(5) In the early stage of the disease, spray Telike 500 times solution, or 20% Lanchao (pyrimethanil) 800 times solution, or procymidone 600 times solution for control.