Prevention and treatment of black-brown rot of celery with small black spots

In the process of celery growth, black heart rot and other symptoms often occur due to bacterial infection, element deficiency and other reasons, so targeted measures should be taken to prevent and cure them.

Black heart rot of celery

First, black rot. The pathogen invaded from the base of celery stem or petiole, fell ill near the ground, and then infected upward, causing heart leaf rot. The part of the disease is black-brown and rotten, sometimes producing small black spots. Prevention and control should be carried out as soon as possible and comprehensive measures should be adopted. The main results are as follows: (1) seed treatment: soak in 48 ℃ warm water for 20 minutes, then move into cold water to cool, remove and dry before sowing. (2) Agricultural prevention and control: use disease-resistant varieties; rotate crops for 2-3 years, preferably in flood and drought rotation; planting density is reasonable to prevent stems and leaves from closing; timely drainage in case of rain in the rainy season, to prevent Rain Water from flowing into the shed, and avoid flood irrigation; in the process of cultivation, the diseased leaves and plants should be removed in time, and the diseased body should be removed immediately after harvest. (3) Chemical control: at the initial stage of the disease, spray control can be done with 50% thiophanate methyl wettable powder or 77% copper hydroxide wettable powder, 50% carbendazim wettable powder, 1500 carbendazim wettable powder, 30% copper oxychloride suspension, 30% basic copper sulfate suspension and 40% chlorothalonil suspension, once every 7 days. Spray 2 times in a row for 3 times.

Second, soft rot. Celery soft rot, also known as "rotten pimple", is a bacterial disease, generally in the ridge shade, the ground is easy to send. Mainly on the base of celery petiole or stem. Prevention and control methods: (1) Agricultural prevention and control: crop rotation for more than two years; in the process of planting, ploughing, weeding and other operations, to avoid root injury or wound. Planting should not be too deep, soil cultivation should not be too high, so as not to bury the petiole into the soil; timely drainage after rain; timely removal of diseased plants, and disinfection such as lime; reduce or stop watering during the disease period to prevent flooding. (2) Chemical control: at the initial stage of the disease, 72% agricultural streptomycin sulfate soluble powder or neophytomycin 3000 × 4000 times solution, 14% complex ammonia copper water agent 350 times solution, 50% copper succinate wettable powder 500 times 600 times solution, spray once every 7 times 10 days, spray 3 times continuously for 5 times.

Third, calcium deficiency. When celery is deficient in calcium, the young tissue of the growth point is brown at first, then blackens, until it dies. At the same time, the disease extends down to the base and root of the stem, so that the stem surface becomes brown and withered, and the growth point is cut open. It can be seen that the interior is hollow, brown and dry, with a slightly sour taste. Control methods: (1) to control the amount of fertilizer, especially in saline-alkali soil, the amount of nitrogen and potassium fertilizer should be strictly controlled to prevent the soil salt concentration in the plough layer from being too high and inhibit calcium absorption. (2) foliar calcium spraying: when celery is deficient in calcium, due to the high concentration of soil solution, soil calcium application is often ineffective. It can be foliar sprayed with 0.3% 0.5% calcium chloride or calcium nitrate solution. (3) calcium-containing fertilizers such as gypsum or lime can be applied to acidic soils with insufficient calcium supply.

Fourth, boron deficiency. Celery is sensitive to boron. Boron deficiency in soil or drought and partial application of nitrogen fertilizer lead to boron deficiency in celery, which will cause stem and petiole cracking, bacteria invade and make celery heart leaves black and rotten. Prevention and control methods: if the soil is boron deficient, 1 kg of borax can be applied per mu to supplement boron; after the symptoms of boron deficiency are found, 0.1%-0.3% borax aqueous solution can be used for foliar spray.