Recently, a pear farmer called the reporter to reflect that his 4 acres of yellow crown pears did not know he had a “strange disease†and the blades were scorching, and a few of them were covered with rust. After investigation, the author discovered that the so-called "strange disease" was caused by Bordeaux liquid injury. At present, the central and southern regions of our province have entered a hot and rainy season, reminding the majority of pear growers to control the time and method of spraying when pests and diseases are to be prevented, and to prevent phytotoxicity due to improper spraying techniques.
In general, when the pears were damaged by phytotoxicity, water-stained green-brown irregular spots appeared on the leaves of the pears, followed by black-brown scorch-like lesions, and the leaf margins and tip parts of the collected liquids were heavier. When the phytotoxicity is severe, the leaf margin is even dry. The damaged fruit forms brown rust or dark brown to black spots. In the near fruit top part, because of the accumulation of the remaining liquid medicine, the lesions are often densely integrated into a circular arrangement. In severe cases, the entire fruit surface is covered with lesions, the skin is hardened, the fruit is not grown, the flesh is rough, and there is often astringency. When the damage is mild, although the fruit shape and flavor are normal, the fruit surface lesions affect the appearance. Of course, because of the many types of phytotoxicity, the symptoms are not exactly the same.
Preventive and remedial measures: Pay attention to changes in leaves and fruits at any time during spraying, and find out that phytotoxicity should stop the use of drugs, reduce the concentration, or correct the wrong method of spraying. Pears are sensitive to copper ions. Bordeaux fluid is used in rainy days and high temperature seasons. Special precautions should be taken. To prevent Bordeaux fluid phytotoxicity, the concentration can be lowered and the amount of lime used can also be increased. Immediately after the occurrence of phytotoxicity, spray fresh water 2 or 3 times, dilute or wash off the pesticide on the leaves or branches, and spray 400-500 times of rice vinegar, which can reduce the harm of phytotoxicity. When the damage caused by pesticide damage is caused by whitening of the leaves, a 50% granular sodium humic acid (first dissolved in a small amount of water, followed by a sufficient amount of water) may be used to spray the leaves on the surface. If the phytotoxicity is caused by an acidic pesticide, 3% to 4% of turfgrass, 0.5% of quicklime or alkaline water may be used for dissolving. If the phytotoxicity is too heavy, then 1% of bleaching powder shall be used for spraying. According to another report, spraying Tianda 2116 400 times can also reduce the phytotoxicity of fruit trees or crops.
In general, when the pears were damaged by phytotoxicity, water-stained green-brown irregular spots appeared on the leaves of the pears, followed by black-brown scorch-like lesions, and the leaf margins and tip parts of the collected liquids were heavier. When the phytotoxicity is severe, the leaf margin is even dry. The damaged fruit forms brown rust or dark brown to black spots. In the near fruit top part, because of the accumulation of the remaining liquid medicine, the lesions are often densely integrated into a circular arrangement. In severe cases, the entire fruit surface is covered with lesions, the skin is hardened, the fruit is not grown, the flesh is rough, and there is often astringency. When the damage is mild, although the fruit shape and flavor are normal, the fruit surface lesions affect the appearance. Of course, because of the many types of phytotoxicity, the symptoms are not exactly the same.
Preventive and remedial measures: Pay attention to changes in leaves and fruits at any time during spraying, and find out that phytotoxicity should stop the use of drugs, reduce the concentration, or correct the wrong method of spraying. Pears are sensitive to copper ions. Bordeaux fluid is used in rainy days and high temperature seasons. Special precautions should be taken. To prevent Bordeaux fluid phytotoxicity, the concentration can be lowered and the amount of lime used can also be increased. Immediately after the occurrence of phytotoxicity, spray fresh water 2 or 3 times, dilute or wash off the pesticide on the leaves or branches, and spray 400-500 times of rice vinegar, which can reduce the harm of phytotoxicity. When the damage caused by pesticide damage is caused by whitening of the leaves, a 50% granular sodium humic acid (first dissolved in a small amount of water, followed by a sufficient amount of water) may be used to spray the leaves on the surface. If the phytotoxicity is caused by an acidic pesticide, 3% to 4% of turfgrass, 0.5% of quicklime or alkaline water may be used for dissolving. If the phytotoxicity is too heavy, then 1% of bleaching powder shall be used for spraying. According to another report, spraying Tianda 2116 400 times can also reduce the phytotoxicity of fruit trees or crops.
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