In addition to applications in medicine, electronic materials, construction, energy, nanotechnology in agriculture is a new direction for the agricultural sector with great potential to replace pesticides and chemical fertilizers; at the same time, it is one of the superior solutions for safe agricultural production and clean agriculture .
According to the assessment of professional sectors, currently, agricultural production increasingly uses chemical fertilizers and pesticides; along with that, farmers' thinking and farming practices are still limited, indiscriminate use of pesticides, chemical fertilizers... Potential risks of harm may be due to overdose, lack of technical knowledge, use of pesticides not following quarantine periods, which has had a negative impact on public health and the environment. As a result, post-harvest agricultural products do not ensure the necessary safety criteria due to residual impurities that can cause poisoning such as NO3- residue, heavy metals, microorganisms... directly affecting the health of consumers. Poor quality food, pesticide residues, food preservatives exceeding the threshold have been a burning issue for a long time. The use of inappropriate fertilizers and pesticides also indirectly harms the economy, when agricultural products with pesticide residues do not meet export standards. Chemical agents in agriculture, when used improperly, will cause environmental hazards. Residual amounts can pollute soil and water, causing ecological imbalance.
Faced with the above situation, the agricultural sector has had many solutions to produce and supply agricultural products that are not only safe for consumers' health but also environmentally friendly. Along with strengthening the inspection and quality control of fertilizers and pesticides; promoting propaganda and advising farmers to use fertilizers and pesticides properly; expanding the production area according to VietGAP and GlobalGAP standards... in recent years, the agricultural sector has promoted the application of new technologies in production, including the application of nanotechnology.
In order to help farmers access and expand the production area applying new technologies in pest control, reducing the rate of fruit drop and cracking, while reducing the amount of chemical pesticides, creating high-quality agricultural products, ensuring food safety and hygiene, protecting the health of producers and consumers, protecting the environment, suitable for concentrated fruit tree production areas that are producing according to VietGAP standards, from 2021 to present, the Department of Agriculture and Rural Development continues to coordinate with relevant units to organize the construction of a pilot model "Application of nano silver and nano copper preparations in preventing fungal diseases, limiting young fruit drop and cracking on longan trees". The model is implemented on an area of 30 hectares at Da Loc Longan Production Cooperative, Dong Vang Cooperative (An Thi), Tien Chau Longan Cooperative (Hung Yen city) with 70 participating households. Along with the amount of nano and fertilizer supported, households are instructed on the process of using nano silver and nano copper preparations with a dosage for 1 spray, mixing 1.5 - 2 liters of nano silver and nano copper solution with 250 - 300 liters of water to spray for 1 hectare. During the young fruit setting stage, spray 2 times, each time 7 - 10 days apart. During the young fruit development stage, spray 5 - 7 times (depending on the severity of the disease) each time 10 - 15 days apart, stop spraying 15 days before harvest. Spray when the weather is clear, in the morning or cool afternoon, limit spraying when the sunlight is strong, which increases the oxidation capacity and reduces the effectiveness of the preparation.
According to the assessment of the Department of Agriculture and Rural Development, periodic spraying of nano preparations has been highly effective in preventing some major fungal diseases on longan trees such as downy mildew, fruit rot, virus broom disease, black fruit disease... The effectiveness of preventing some major pests and diseases on longan trees shows that nano silver and nano copper preparations have effects equivalent to some chemical drugs currently used locally with the same number of sprays. However, through monitoring, it shows that the effectiveness of nano silver and nano copper is slower in controlling diseases when disease pressure is high. Regarding the rate of fruit set and preventing young fruit drop, nano silver preparations, in addition to preventing and controlling diseases, also supplement some other trace elements such as (Ca, Bo) which play a role in supplementing and balancing nutrition for tree growth and development, especially during the flowering and young fruit setting stages; helps flower clusters grow large and strong, balances the ratio of male and female flowers, enhances the function and vitality of pollen, promotes pollination, flower buds develop, increases fruit set rate, prevents young fruit from falling, and limits the harmful effects of acid rain that damages flowers and young fruit. Therefore, the fruit drop rate (10%) is lower than the conventional farming model of farmers (15 - 20%). Because nano silver and nano copper preparations have the effect of killing bacteria and fungi on the fruit, the fruit peel is bright and thick, reducing the rate of cracking and fruit drop. In addition, the fruit ripening time is longer than the conventional intensive farming method by 3 to 5 days, thereby reducing the pressure on harvest time. Nano preparations are safe for producers, do not cause residues, drug resistance, do not affect the environment and beneficial organisms, and are suitable for longan production areas according to VietGAP standards.
Dao Ban
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