The efficacy of plant growth regulators is affected by many factors, such as crop variety, growth cycle, application site, regulator variety, application concentration, application method and external natural conditions. Therefore, there are high requirements for the use technology of plant growth regulators. Once there is an error, it may cause pesticide damage to crops and cause unnecessary losses. The problem of drug damage is a prominent problem in the use of plant growth regulators. Common drug damage mainly includes the following reasons:

1. Incorrect usage period

The use of plant growth regulators is subject to strict requirements. Once the application period is inappropriate, it will cause drug damage, which may result in reduced production in the light and no harvest in the heavy.

Case 1: Application of Timuride on Watermelon

In late May 2011, the "Japanese all-around champion" watermelon of Liu Mingxu, a villager of Dalu Village, Yanling Town, Danyang City, Jiangsu Province, burst due to the use of "watermelon expander".

People are accustomed to think that puffin is the culprit that causes watermelon to crack. In fact, watermelon cracking is not caused by the use of watermelon expander. Watermelon expander itself is not a problem, but because it is used in an incorrect period of use. The main component of watermelon expander is clopidomide, also known as clopidomide and KT-30. Its correct use period is to dip the melon embryo at the concentration of 10-20mg/L on the day or one day before and after the flowering of watermelon, which can play the role of expanding watermelon, increasing sugar content, reducing the number of melon seeds, uniform melon shape, and beautiful appearance. When the diameter of watermelon is more than 15cm, it can't be used again, otherwise it will cause drug damage, specifically manifested as hollow watermelon, loose gourd gourd gourd, decreased sweetness, poor taste, and more serious, it will lead to watermelon cracking. At the same time, because clopidomide is not conductive, it is easy to cause abnormal melon if it is not evenly stained. The melon grower used watermelon expander at the wrong time, not only did not play the role of clopidomide, but also caused drug damage.

Case 2: The application of chlormequat in cotton

In the middle of June 2010, a cotton farmer in Handan, Hebei, said that the cotton he planted would not grow when it grew to 20 cm high, forming a stiff plant. After detailed inquiry, we learned that it was caused by the incorrect period of application of chlormequat. CCM has a good effect on controlling cotton growth and promoting high yield of cotton. The correct use period is to spray 100~200mg/L of CCM when the cotton grows 6~7 fruit branches, which can effectively control cotton growth, make the main stem of cotton stretch slowly, plant dwarf, fruit branches shorten, and plant type compact, which is conducive to ventilation and light transmission in the field, promote cotton photosynthesis, and increase yield significantly. However, when the cotton plant just grew to 20 cm, the cotton farmer saw that the cotton plant was growing vigorously, and sprayed 150 mg/L of chlormequat, which caused the cotton to stop growing, resulting in stiff plants.

2. Incorrect dosage

The dosage of each plant growth regulator is strictly limited. If used low, the effect will not be achieved. If used high, the drug damage will occur.

Case 1: Application of sodium nitrate and naphthoic acid in peach trees

In May 1998, a fruit farmer in Shandong Province used 2.85% sodium nitrate and naphthylacetic acid on the peach trees in the greenhouse, causing all the young peach trees in the six greenhouses to fall off, and some even the leaves to fall off. The reason for this phenomenon is that the use concentration is incorrect. When spraying 2.85% sodium nitrate and naphthoic acid aqueous solution at the young fruit stage of peach, it should be diluted by 4000 times to spray the whole plant, which can play the role of expanding fruit, beautifying fruit and improving taste. However, the fruit farmer only diluted by 1500 times when using it, and the use concentration is too high, resulting in all the young peaches falling off, and the six greenhouses are basically out of harvest..

Case 2: Coloring application of ethephon on grapes.

In 2010, a fruit grower in Mianyang, Sichuan reported that the grapes he planted fell off before they were fully mature. Ethephon has a good effect on promoting grape coloring. Different grape varieties have slightly different concentrations. For example, Jufeng grape can ripen 6 to 8 days earlier by spraying the ear at a concentration of 250~300mg/L at the beginning of ripening, and the uniform color is good. However, the use of ethephon will cause separation between grains and fruit stalks, which will lead to seed falling. Therefore, it is necessary to grasp the concentration, spray, harvest and sell in stages to avoid losses. The fruit grower blindly expanded the use of concentration, and uniformly sprayed 500 mg/L of ethephon on grapes of different varieties and different growth periods, resulting in a large number of seed falling.

3. The dosage of plant growth regulators on different crop varieties is different

Because different crop varieties have different sensitivities to the growth regulation of the same plant, the plant growth regulator should be tested before being popularized.

Case 1: Application of NAA on different varieties of watermelon

In 2009, a melon farmer in Nanjing reported that the watermelon leaves turned over overnight after spraying 10 mg/L of NAA when the diameter of the watermelon was about 10 cm.

Naphthylacetic acid is a good flower and fruit preserving and expanding agent. It is one of the early plant growth regulators used in China. In the 1960s, China began to synthesize and use naphthylacetic acid, which plays a great role in cotton flower and boll protection, fruit tree flower and fruit thinning, flower and fruit thinning. The use of 10mg/L naphthylacetic acid on cotton, most fruit trees (except peach trees) and melons (except watermelon) can play a role in flower and fruit preservation, fruit expansion Watermelon is sensitive to the effect of coloration. The high concentration is 8mg/L. If the concentration is more than 8mg/L, the damage will occur. When the concentration is 10-15mg/L, the watermelon leaves will reverse. When the concentration is 15-20mg/L, the watermelon will wilt. When the concentration is more than 20mg/L, individual watermelon varieties will die. The farmer sprayed the melon at a concentration of 10mg/L according to the instructions, ignoring the particularity of watermelon, which led to the phenomenon of watermelon leafing.

Case 2: Application of prochloraz DA-6 in different peach varieties

In 2007, more than 10000 mu of peach trees were planted in a certain area of Dalian, and a concentration of 10mg/L of prochloraz was uniformly sprayed during the young peach period. The results showed that the effect of prochloraz on flat peach and long-lived peach varieties was significant, but the leaves of nectarine appeared bean-size spots. After the test, it was proved that the concentration of prochloraz DA-6 in nectarine was 6mg/L, and the leaf spots would appear when the concentration of prochloraz DA-6 was 10mg/L.

Dichloraz is a broad-spectrum plant growth regulator with a long period of use. It can be used for seed soaking, seedling, growth and flowering spraying. It is safe to use. There have been no reports of pesticide damage of Dichloraz. We have found that only when the concentration exceeds 50mg/L, the growth of some varieties of crops will be inhibited.

4. Incorrect use method

When the same plant growth regulator is applied to the same crop, it will also cause drug damage if it is used improperly.

Case 1: Application of clopidomide KT-30 on zucchini

In December 2008, vegetable farmers in Shouguang, Shandong Province reported that all the zucchini they planted in the greenhouse had deformed melons, all of which were gourd-shaped, with big heads. It was found that it was caused by improper use of clopidomide. The correct way to use clopidomide on zucchini is to soak the melon embryo with a concentration of 10mg/L when the zucchini blooms for 1 to 2 days, which can play an obvious role in fruit expansion and fruit homogenization, so as to market early. The melon was dipped with the liquid medicine in a disposable paper cup. Due to the small mouth of the cup, only the lower part of the melon embryo was stained when dipping the fruit. Due to the non-conductivity of clopidomide, the cells in the stained part split quickly and expanded rapidly, and the non-stained part continued to grow normally. Therefore, all the pickled zucchini grew into gourd shape, with a large head.

Case 2: Application of gibberellin in grapes

In 2006, some fruit farmers in Turpan, Xinjiang, reported that the use of gibberellin in grapes planted by them resulted in very uneven grains, which seriously affected the yield and quality. After investigation, it was caused by improper use of gibberellin. The application of gibberellin on grapes has significant effects on enlarging ear length, increasing fruit grain, early ripening, increasing sugar and fruit acid content, and its performance is also relatively stable. The correct use method is to dip the ear with 150mg/L concentration 10~20 days after the full flowering of grapes. The farmer sprayed the ears with a spray, which resulted in large grains on the treated ears and small grains on the untreated ears. Grape grains on the same ear were large and small. Grape grains on different ears were also different in size, seriously affecting the yield and quality of grapes.

5. Use at will

The compound application technology of plant growth regulators has been verified through strict formula screening and field tests, and can play a synergistic role. For example, 2.85% sodium nitrate. naphthylacetic acid aqueous solution, 30% ammonium salt. ethephon aqueous solution and so on are all good compound preparations of plant growth regulators, but not all plant growth regulators can be combined.

Case 1: The wrong application of the compound of sodium dinitrophenol and thiofenone on flammulina velutipes

In 2006, some vegetable farmers in Luoyang reported that the 5-mu goldenrod they planted sprayed with sodium dinitrophenol and thiophene at the same time during the blooming period, resulting in the withering and withering of goldenrod.

Spraying 6~9mg/L sodium nitrophenolate on the goldenrod can increase the flow of cytoplasm, promote the absorption and operation of other chemicals and fertilizers in the crop, make the flowers even and fat, and play a role in increasing production; Spraying 1 mg/L concentration of thiabenduron can make the plant robust and reduce flower bud shedding. However, the combination of the two can produce side effects such as wilting and withering and even killing the goldenrod under adverse climatic conditions.

Case 2: The wrong application of the combination of chlormequat and acetaminophen in cotton

In 2010, some farmers in Hebei reported that the 10 mu cotton they planted grew grew slowly and the petiole became brittle after being sprayed with chlormequat and chlorhexidine at the same time.

Both chlormequat and acetaminophen can promote the slow extension of cotton main stem, dwarf the plant, shorten the fruit branch, and make the plant compact, which is beneficial to the ventilation and light transmission in the field, promote the photosynthesis of cotton, and increase the yield. However, when the two are used in combination, they can only play a role in controlling the growth and yield within the appropriate concentration range. The farmer used the normal concentration of chlormequat and chlorhexidine on cotton at the same time, resulting in the cotton stop growing and the petiole become brittle.

6. Other non-standard drugs

Different use methods, time and concentration of the same agent will play different roles. If it is used wrongly, it will cause harm. For example, paclobutrazol is used on apple trees. When the apple trees have grown into productive plants, the growth of apple trees in the second year can be effectively controlled by applying 2~3g paclobutrazol to the roots around 1.5 meters around the tree for one week in autumn, which is still effective in the third year; When the apple treetop grows to 5~10 cm, the growth of the apple treetop can be controlled by spraying with a concentration of 300 mg/L; The growth of the current year's shoots can be controlled by scraping the bark of the trunk 20~30 days after the flowering of the apple tree in the Spring Festival and brushing the trunk with a concentration of 1000mg/L, which is still effective in the next year. If the usage and dosage are not correct, it will have no effect or even cause drug damage. For example, spraying 1000 mg/L paclobutrazol on apple trees will seriously hinder growth, lead to yield reduction and fruit quality decline.

Environmental conditions also directly affect the use effect of plant growth regulators. For example, if the temperature is lower than 20 ℃ or higher than 35 ℃, the effect of naphthoic acid on tomato fruit preservation is not good; When the temperature is 25~30 ℃, the wrapping effect is very good. Another example is that clopidomide should be used on the day when the cucumber blooms. If it is used on the day when the cucumber has reached about 10cm in length or later, the cucumber placed in the refrigerator is still growing, but the taste is poor and the quality is decreased.