The Latest Technical Methods and Tutorial for Pest and Disease Control in Water Spinach
Water spinach, originally named swamp cabbage, also known as rattan vine spinach, water spinach, tong cai, wu xin cai, weng cai, kong tong cai, bamboo leaf vegetable, jie jie cai, etc., prefers high temperature and humid environments, suitable for moist soil, likes sufficient light, has no strict requirements for soil conditions and likes fertilizer and water, bears white trumpet-shaped flowers and its stem center is hollow, hence called “water spinach”. It is widely cultivated as a vegetable in rural areas of southern China. Now let us take a look at the pest and disease control techniques for water spinach!
Water Spinach Brown Spot
[Damage Symptoms] The lesions on the leaves are nearly circular, sometimes restricted by large leaf veins and becoming semicircular or irregular, with a lesion diameter of up to 5-10 mm. The lesions are brown, dark brown or reddish brown, varying depending on the variety, usually with darker edges and lighter centers. Most lesions have a small nested spot in the center, which is lighter in color with darker edges, and several lesions can merge into larger patches. After the lesions develop along the main vein, the leaves may become distorted. When dry, the center of the lesion cracks. When moist, black mold-like growth appears on both sides of the lesion.
[Causal Pathogen] The pathogen overwinters in diseased plant residues, and the residues produce conidia that spread with wind and rain, causing primary infection. After the plant becomes diseased, conidia are produced on the lesions and continue to spread and infect. Multiple re-infections can occur in one growing season.
[Agricultural Control] (1) Reasonable fertilizer and water: fertilize reasonably according to variety characteristics, increase the application of decomposed organic fertilizer, pay attention to the combination of nitrogen, phosphorus and potassium, prevent the plants from running out of nutrients, water reasonably, do not over-irrigate, drain promptly after rain, and reduce humidity. (2) Remove old leaves: implement a rotation of more than 2 years in severely diseased fields, and promptly remove diseased old leaves at the base of the plants. (3) Clean the field promptly: after harvest, promptly remove diseased residues, deep plow and sun-dry the soil, and eradicate field weeds.
[Chemical Control] At the early stage of disease, you may choose to spray 25% triadimefon wettable powder at 1200-1500 times dilution, 50% iprodione wettable powder at 1000-1300 times dilution, 70% mancozeb wettable powder at 600 times dilution, 65% zineb at 500-600 times dilution, 70% thiophanate-methyl wettable powder at 600 times dilution, or 75% chlorothalonil wettable powder at 500 times dilution, etc. Spray once every 7-10 days, for 3-4 applications.
Water Spinach White Rust
[Damage Symptoms] Water spinach white rust mainly damages leaves. When the disease occurs, pale yellow-green to yellow spots appear on the upper surface of the leaves, later turning brown. The lesions are relatively large, and the underside of the leaves shows raised blister-like spots, nearly round or oval or irregular. When the leaves are severely damaged, the lesions are dense, the diseased leaves are deformed and fall off, and the stems swell and deform, thickening 1-2 times.
[Disease Conditions] The disease is most likely to occur at a temperature of 20-35 degrees.
[Chemical Control] Use 35% metalaxyl seed dressing agent at 0.3% of the seed weight. At the early stage of disease, spray 58% metalaxyl-mancozeb wettable powder at 500 times dilution, 40% fosetyl-aluminum (shuangyiling) wettable powder at 250-300 times dilution, once every 7-10 days, for 2-3 consecutive applications.
[Agricultural Control] Use disease-free seeds, and a 2-3 year rotation gives good disease control results. Pay attention to field drainage and ventilation, and reasonably arrange the spacing density.
Water Spinach Anthracnose
[Damage Symptoms] Water spinach anthracnose mainly damages leaves and stems, and seedlings are prone to death when affected. When leaves are infected, the lesions are nearly circular, dark brown, with faint concentric rings on the surface and densely scattered small black dots. The lesions expand and merge, and the leaves turn yellow and dry up. The lesions on the stems are nearly oval and slightly sunken inward.
[Disease Conditions] High temperature and rain, excessive nitrogen fertilizer application, overly vigorous growth, and overlapping stems and leaves that block light make the disease likely to occur.
[Control Methods] At the seedling bed stage and the early stage of disease in adult plants, spray 70% carbendazim wettable powder at 800-1000 times dilution or 50% thiram powder at 600-800 times dilution, 40% carbendazim-sulfur suspension concentrate at 500-600 times dilution, 77% copper hydroxide at 600 times dilution, 10% difenoconazole water-dispersible granules (Shigao) at 50-75 grams/mu, 80% Bordeaux mixture wettable liquid (Bibei) at 300-500 times dilution, 25% bromothalonil wettable powder (Tanteling) at 2000-2500 times dilution, once every 10 days, for 2-3 consecutive applications, and stop applying the chemical 5 days before harvest.
Water Spinach Ring Spot
[Damage Symptoms] Water spinach ring spot mainly damages leaves. Initially small brown spots appear on the leaves, and after expanding they become circular, oval or irregular, reddish brown or light brown. The lesions are relatively large, with obvious concentric rings, and later small black dots appear on the ringed lesions.
[Disease Conditions] The disease is likely to occur in rainy seasons and in fields with dense, closed growth.
[Chemical Control] At the early stage of disease, spray 1:0.5:160-200 Bordeaux mixture or 45% amobam aqueous solution at 1000 times dilution, or 75% chlorothalonil wettable powder at 600-700 times dilution, or 58% metalaxyl-mancozeb wettable powder at 500 times dilution, 50% prochloraz wettable powder (Baolido) at 35-75 grams/mu, 70% propineb wettable powder (Antaisheng) at 150-220 grams/mu, 10% difenoconazole water-dispersible granules (Shigao) at 35-50 grams/mu, once every 7-10 days, for 2-3 consecutive applications.
[Agricultural Control] In winter, remove fallen dead leaves and diseased residues from the ground, and combine this with deep plowing to accelerate the decomposition of the residues. A 1-2 year rotation can be implemented.
Water Spinach Leaf Roller
[Damage Characteristics] Newly hatched larvae mostly stay in the heart leaves and tender leaf sheaths of rice seedlings, as well as in old larval nests and the rolled leaf tips damaged by rice thrips, gnawing on the leaf mesophyll and appearing as small white dots. Second-instar larvae gnaw the mesophyll and leave the epidermis, appearing as short white strips, and spin silk to roll the leaf tip longitudinally for 1.5-5 cm. Third-instar larvae gnaw the mesophyll and appear as white patches, rolling the leaf longitudinally with a larval nest 10-15 cm long. Larvae of the fourth instar and above feed voraciously on the leaves, eating the mesophyll and leaving the epidermis. One larva can eat 6-10 rice leaves.
[Agricultural Control] (1) Use bundles of grass or piles of grass to trap overwintering mature larvae. (2) In autumn and winter, promptly capture and kill overwintering larvae in fallen leaves, cracks or near buildings, and in summer promptly capture and kill newly hatched larvae, removing damaged leaves when necessary. (3) Set up black light lamps to trap and kill adults.
[Chemical Control] In the three-generation occurrence area around Shandong, and the four-generation occurrence area in Jiangsu and Zhejiang, attention should be paid to controlling the 3rd and 4th generations. Before the larvae roll the leaves at the end of the 2nd instar, spray 80% dichlorvos emulsifiable oil at 1000 times dilution or 60% dimehypo emulsifiable oil at 1500 times dilution, 90% crystal trichlorfon at 1000 times dilution, 25% phosmet emulsifiable oil at 1000 times dilution, 5% fipronil suspension concentrate at 1500 times dilution, 50% phoxim emulsifiable oil at 1000 times dilution.