Humic acid, a natural high molecular organic compound, has been widely applied in fruit protection due to its unique physical and chemical properties such as adsorption and complexation. This article elaborates on the specific application methods of humic acid in fruit protection, focusing on its advantages including cost reduction, environmental friendliness, and quality improvement, as well as the practical effects in disease resistance, crack prevention, and quality enhancement. Taking blueberry as a typical example, the application value of humic acid is highlighted. Finally, common questions about humic acid application are answered to provide a comprehensive reference for fruit growers and related practitioners. The total word count is about 800.
Humic acid is mainly applied in fruit protection in two forms: one is as a component of organic functional fertilizers, which is applied to the soil to improve fruit tree vitality and enhance fruit peel toughness from the root; the other is as a liquid film agent, which is sprayed on the surface of young fruits to form a protective film. For soil application, humic acid is usually mixed with nitrogen, phosphorus, potassium and trace elements to make chelated fertilizers, which are applied during fruit tree growth periods. For foliar spraying, food-grade humic acid is mixed with trace element reagents to form a liquid film, which is sprayed evenly on the fruit surface at the early stage of fruit development, and the spraying can be repeated 2-3 times according to the growth situation.
Compared with traditional fruit protection measures such as bagging, humic acid has obvious advantages. Firstly, it is environmentally friendly and safe. The humic acid film agent is degradable and will not cause environmental pollution, and its food-grade raw materials ensure no harmful residues on the fruit surface. Secondly, it reduces costs significantly. It avoids the high labor cost of manual bagging and bag purchase cost, and can be applied by mechanization. Thirdly, it has dual functions of protection and nutrition. While forming a protective film on the fruit surface, humic acid can also provide nutrients for fruit growth, realizing the integration of protection and nourishment. Fourthly, it has strong adaptability, which is suitable for various fruits such as blueberry, apple, cherry and grape.
The application of humic acid in fruit protection has achieved remarkable effects. In terms of disease resistance, the humic acid film can block the invasion of pathogenic microorganisms such as Penicillium crustosum and Aspergillus tubingensis, reducing fruit rot rate. In terms of crack prevention, it can enhance the toughness and elasticity of the fruit peel by promoting the absorption of calcium, potassium and other elements by fruit trees, thereby reducing fruit cracking caused by temperature changes or excessive water absorption. In terms of quality improvement, it can adjust the fruit’s respiratory balance, make the fruit color more natural and uniform, and increase the sugar content by 1-2 percentage points. In addition, it can also improve the water retention capacity of fruits, helping them resist drought stress.
Blueberry is a berry with thin peel, which is prone to cracking, rot and pest infestation during growth and storage, affecting yield and quality. The application of humic acid has effectively solved these problems. In a blueberry orchard in Lushan County, humic acid-rich peat soil is used to improve the planting soil, which not only improves the soil’s water retention and air permeability but also provides continuous nutrients for blueberry growth. At the same time, humic acid liquid film agent is sprayed on young blueberries. The results show that the blueberry rot rate in the test area is reduced by 40% compared with the control area without humic acid application, and the cracking rate is reduced by 55%. The mature blueberries have larger fruit size, higher sugar content (increased by 1.8 percentage points on average), and brighter color. In terms of cost, the use of humic acid reduces the manual weeding and bagging costs by about 800 yuan per mu, significantly improving the economic benefits of blueberry planting.
Q1: What is the best time to spray humic acid film agent on fruits? A1: The best time is 7-10 days after fruit setting, when the young fruit is small and the surface is smooth, which is conducive to the formation of a uniform film. Avoid spraying in strong sunlight or rainy days. Q2: Can humic acid be mixed with pesticides? A2: Yes, but it should be noted that humic acid is alkaline, so it should not be mixed with acidic pesticides. It is recommended to conduct a compatibility test before mixing to ensure no precipitation or deterioration. Q3: How often should humic acid fertilizer be applied in soil? A3: It is usually applied twice a year, once in the spring germination period and once in the fruit expansion period. The specific dosage should be adjusted according to the fruit tree variety and soil fertility. Q4: Is humic acid suitable for all fruit varieties? A4: It is suitable for most fruit varieties, especially berries and stone fruits with thin peels such as blueberry, cherry, and grape, which have more obvious protection effects.
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