In fruit and vegetable cultivation and management, flower and fruit preservation and promoting fruit enlargement have always been major concerns , especially when pollination conditions are poor, such as rain or low temperatures, which can easily lead to flower and fruit drop and affect yield. Chlorpyrifos, also known as CPPU, is a widely used plant growth regulator on the market. Many agricultural growers use it for scientific crop management, but they sometimes fail to identify the appropriate application period, resulting in hollow or deformed fruits. Many people also mistakenly believe it to be a ripening agent.
This article will explain the characteristics, applicable crops, and key points of scientific application of chlorpyrifos, helping you avoid common mistakes in pesticide use and better leverage its effects on improving quality and increasing yield while ensuring compliance and safety.
What is chlorpyrifos?
Chlorpyrifos is a broad-spectrum, multi-purpose substituted urea plant growth regulator with benzylaminopurine activity. It is currently the most potent human synthetic furfurylaminopurine in promoting cell division, with a biological activity approximately 10 times that of benzylaminopurine. It is primarily absorbed through the roots, stems, leaves, flowers, and fruits of plants and then transported to the sites of action. Simply put, it mainly helps increase the normal cell division of fruits; when used properly, it can assist in flower and fruit retention and promote the enlargement of young fruits. Many grape, kiwi, and melon growers use it. However, its effectiveness is highly dependent on its application; incorrect timing or concentration can easily lead to problems such as hollow or deformed fruits, which will be the focus of our discussion later.
Mechanism of action and core efficacy
The main physiological function of chlorpyrifos is to promote cell division, increase cell number, and enlarge fruit. Many growers use it to soak young kiwifruit after flowering and to promote fruit enlargement in Shine Muscat grapes. When used properly, it results in more fruit cells, significantly increasing single fruit weight and marketable fruit rate, rather than simply "stretching and enlarging" cells. It can also promote tissue differentiation and development, break lateral bud dormancy, and promote germination. For some kiwifruit varieties with weak budding, proper bud treatment can promote new branches and help the canopy shape faster. At the same time, it can regulate the transport and distribution of nutrients within the tree, directing more nutrients produced by photosynthesis in the leaves to the flowers and fruits, and delaying leaf and fruit senescence. This reduces premature yellowing of leaves and fruit drop before harvest, and improves the storage and transportability of harvested fruit. When flowering coincides with continuous rain and low temperatures, hindering insect pollination, chlorpyrifos can improve pollen fertility and induce parthenocarpy in crops such as watermelon, cucumber, and grapes. Even under poor pollination conditions, it can successfully set young fruit, reducing large-scale flower drop and fruit abortion losses. However, it is important to reiterate that all effects are based on appropriate concentration, correct timing, and proper water and fertilizer management; simply using it does not guarantee good results.
Scientific usage guidelines for chlorpyrifos
Applicable crops:
Chlorpyrifos (CPPU) is widely used in fruits and vegetables, with varying application methods and timing depending on the crop. Common applications include: Grapes are a very common crop for which it is used, especially varieties like Shine Muscat and Summer Black, often in combination with gibberellin for fruit preservation and expansion. Kiwifruit is another classic example, typically used to soak young fruit after flowering to increase fruit size. Various melons, including watermelons, cantaloupes, and cucumbers, are also frequently used to protect fruit buds and reduce fruit drop when pollination is poor due to rainy weather. In addition, loquat, pear, and citrus trees may also use it as appropriate during the fruit preservation stage. Some farms also use it on certain vegetables and specialty berries to aid fruit setting.
Application method:
Chlorpyrifos is mostly used by dipping fruit clusters, young fruits, or melon buds, and is rarely used for direct foliar spraying of the entire plant. This is because it only needs to act on the flower and fruit parts; spraying the entire tree can easily stimulate buds and new shoots, causing side effects. The application methods and timing vary greatly depending on the crop.
For example, grapes: the bunches are usually soaked 10-15 days after flowering, often in combination with gibberellic acid. When soaking, completely submerge the bunches in the solution for a few seconds, then lift them out and drain off the excess solution . Do not repeatedly soak the bunches.
Kiwifruit: Choose a sunny day, 20-25 days after flowering, to treat the young fruit by soaking. Only use this treatment once per season. When soaking, make sure to coat the fruit surface evenly and avoid accumulating too much solution at the fruit stem. Too high a concentration or repeated soaking can easily cause the fruit to become hollow.
Watermelon, cantaloupe, cucumber: mostly apply the solution to the fruit embryo, that is, the young fruit, on the day the female flower opens or the day before or after. Only treat the fruit embryo and try not to get the solution on the tender leaves and growing points of the vine. The effect is more obvious when pollination is difficult due to low temperature and rain.
For fruit trees such as loquat, pear, and citrus: the main method is to apply pesticides to young fruits to preserve the fruit. The application period is concentrated in the young fruit stage after flowering.
Precautions:
• Strictly follow the prescribed time, dosage, and method of application. Excessive concentration can cause hollow fruit, deformed fruit, and top cracking, and also affect the vitamin C content in the fruit.
• It is irritating to human eyes and skin; precautions should be taken when applying it.
• When chlorpyrifos is mixed with gibberellic acid or other auxins, its effect is better than using them alone, but this must be done under the guidance of professionals or after trial and demonstration; do not mix them arbitrarily. When combined with potassium dihydrogen phosphate, it can promote fruit enlargement, promote plant growth, prevent fruit drop, and effectively improve fruit quality. When used on wheat and rice, it can increase the thousand-grain weight, thus increasing yield Effect.
·If it rains within 12-24 hours after treatment, the pesticide must be reapplied.
·The solution should be prepared fresh each time it is used; otherwise, its effectiveness will be reduced. This product is volatile, so the cap should be tightly closed after use.
