Analysis of the Reasons Why Pepper Phytophthora Blight Is Never Cured

In Dongyi Village, Daotian Town, Shouguang City, a fairly wide variety of crops is grown, with tomatoes, peppers and cucumbers each showing their strengths. Old Wang in the village got a taste of success from growing peppers last year, so this year he planted peppers again.

But recently, Old Wang has not been able to "taste the sweetness." Why? The peppers he planted showed symptoms of wilting, and this frightened him badly. "Peppers are most afraid of phytophthora blight; if it is not handled well, most of the plants in this greenhouse could be lost," said Old Wang. What puzzled Old Wang most was that he had done no small amount of disease prevention work in the early stage, right? He chose disease-resistant varieties, and when transplanting he even applied phosethyl-Al in the planting holes, so how could phytophthora blight still occur? No matter how it happened, he still had to treat it quickly! He hurriedly bought pesticides from the agricultural supply store, spraying and drenching the roots, using everything that could be used. But the peppers still died at a rate of about 7 or 8 plants every day, and now Old Wang was truly at his wit's end.

It just so happened that the Shouguang City Vegetable Association had an expert hotline, so he quickly called for help! After receiving the call, staff from the Shouguang City Vegetable Association rushed to the greenhouse and clarified the whole story. It turned out that when Old Wang saw the peppers dying, he became anxious and, relying solely on past years' experience, assumed that the peppers had phytophthora blight, which was why the effect after drenching with pesticide was minimal.

According to observation, the peppers in this greenhouse showed no problems at all in the morning. Once noon came, the plants wilted; especially when the light was strong, the wilting became more severe. By evening the plants returned to normal. From onset to death, the plants took between 10 and 20 days. In places with high humidity, the disease was severe. The experts preliminarily determined it to be root rot.

In order to understand the condition more accurately, staff from the Shouguang City Vegetable Association got a shovel, dug up the affected plants whole with soil, then washed the soil off with water, keeping all the pepper roots. Upon observation, the root crown and root epidermis of the diseased plants had already become light brown to dark brown and rotten, and the epidermis could be peeled off, while the xylem had turned dark. This was typical pepper root rot.

Since an accurate diagnosis had been made, it was time to move quickly on prevention and control. Staff from the Shouguang Vegetable Association then gave a detailed prevention and control plan:

Use Xiangnong No. 4 at 600 times dilution for root drenching. Note that the affected plants should be drenched first. When drenching, first push aside the soil around the pepper roots a little to slightly expose part of the root system, then pour the pesticide solution into the prepared pit. Generally, the amount of solution used per plant is about 250 grams. After the solution seeps in, cover it with soil again. The purpose of doing this is to allow the solution to seep in better and let the roots absorb it fully, thereby playing a protective and therapeutic role.

You can also use hymexazol and propamocarb for root drenching, using the same method as above. After 5 days, carry out root drenching once more. Two to three consecutive times is enough to prevent root rot pathogens from infecting the plants again.