Causes and Control Methods of Dry Shrinkage of the Central Leaves of Hot Peppers

At present, temperatures are gradually dropping, with occasional foggy weather, causing frequent diseases in hot peppers grown in greenhouses. Recently, vegetable growers have often reported problems encountered when growing hot peppers. The problems that have occurred with hot peppers recently are summarized below for the reference of fellow vegetable growers:

Dry shrinkage of the central leaves of hot peppers

A vegetable grower from Wutai, Shouguang City, called to ask about dry shrinkage occurring in the central leaves of the hot peppers being grown, and whether it was a viral disease.

Dry shrinkage of the central leaves of hot peppers may be caused by a viral disease. After peppers are infected by a virus, a variety of symptoms can appear, generally including mosaic, fern leaf, vein clearing, dwarfing, yellowing, necrosis, and bud blight, among which the one that can cause dry shrinkage of the central leaves of hot peppers is fern leaf virus disease. After this viral disease occurs, diseased plants show symptoms of systemic wrinkling and dwarfing to varying degrees, with increased branching, presenting a bushy appearance; the mesophyll tissue of the central leaves degenerates, the leaves become smaller or fern-like leaves appear, and in the later stage the diseased plants become twisted and deformed. If the symptoms of hot peppers are similar to the above situation, it is very likely a viral disease, and control can be carried out according to the following methods: (1) 20% Virus A wettable powder at 500 times dilution; (2) Bingdujing or Bingduling at 500 times dilution; (3) 1.5% Zhibingling emulsion at 1000 times dilution; (4) Antiviral Agent No. 1 at 400 times dilution, sprayed once every 10 days, for 3 consecutive sprays.

Leaf shrinkage of new leaves caused by pesticide damage: Mite damage can also cause dry shrinkage of the central leaves. The specific symptoms are that the hot pepper leaves are dark green, becoming thicker and more brittle, with an oily sheen on the underside of the leaves. When mite damage is severe, it causes leaf curling, and mite activity can be clearly seen under a high-power magnifying glass or microscope. For mite damage, pesticides such as Sunman, Abamectin, and Aifuding No. 1 can be sprayed for control.

In addition to the above two causes, Teacher Liu Mingjie, chief expert of the Shouguang City Vegetable Association, also put forward the following viewpoint: pesticide damage may also cause shrinkage of the central leaves of hot peppers.

Pesticide damage is divided into two types: one is hormone poisoning caused by improper concentration of hormone use, and the other is pesticide damage directly produced by excessive concentration when spraying. Hormone poisoning mainly occurs on the young and tender central leaves near the growing point, with leaf veins turning over and twisting, leaves thick and stiff, color deepening, and leaf margins curling upward. Leaf curling, hardening, and dark green discoloration appear near the fruit at the flower-dipping site.

According to Teacher Liu, the above phenomena are mostly caused by spraying too much hormone. The dry shrinkage and curling deformation of leaves near the growing point are due to poisoning caused by excessive accumulation of hormones at the top of the plant. To avoid dry shrinkage of the central leaves caused by hormones, the concentration of hormones used should be strictly controlled. Try not to use preparations containing hormones. If hot peppers show excessive vegetative growth, Fengshou No. 1 at 800 times dilution can be sprayed for control; this product contains no hormones and can be used with confidence.

The other type of pesticide damage is the damage directly produced when spraying. Normally, when vegetable growers prevent or control diseases, they use pesticides such as metalaxyl mancozeb, Kelu, and mancozeb for control, and long-term use of mancozeb-type pesticides is very likely to cause pesticide damage. Nowadays, vegetable growers are so afraid that once a disease occurs seriously it cannot be cured that as soon as a disease occurs mildly, they immediately use strong pesticides for control. The lower old leaves may still tolerate it, but the upper young and tender leaves are very likely to suffer pesticide damage, causing dry shrinkage of the central leaves. After pesticide damage occurs, Fengshou No. 1 at 800 times dilution or Aiduoshuo can be sprayed to alleviate it, so as to avoid the plant growth being affected by pesticide damage.

Viral disease of bell peppers occurs sporadically

When the author was visiting Shili, Shengcheng Subdistrict, Shouguang City, a vegetable grower held two bell peppers and asked what disease they had. The diseased bell peppers were covered with brown streaks, and after cutting them open the flesh inside showed no change at all. It is understood that the leaves of the plants with streaked bell peppers also showed no adverse symptoms; there were only brown stripes or yellowish-brown spots one by one on the fruit. According to the diagnosis of relevant vegetable experts from the Vegetable Association, this is bell pepper streak virus disease. Commonly known as yellow tip, this is exactly the period when this type of disease occurs, so attention should be paid to doing a good job in preventing and controlling viral diseases and striving to minimize losses. Viral diseases are mainly spread through infection of viruses through wounds caused by insects or friction.