Insect-proof Net Room Cultivation Techniques for Dongkui Waxberry: Experience from Huangyan, Taizhou
Insect-proof Net Room Cultivation Techniques for Dongkui Waxberry in Huangyan District, Taizhou City
The insect-proof net room (also called luozhang or luoman) cultivation technique for Dongkui waxberry is an emerging eco-friendly green cultivation technique that uses insect-proof net rooms to build an artificial barrier and isolate pests such as waxberry fruit flies outside the net. With this technique, no pesticides are used during the fruit ripening process of Dongkui waxberry, ensuring fruit quality and safety, improving fruit quality, and increasing economic benefits. For this reason, in recent years Huangyan District has actively promoted the construction of single-tree insect-proof net rooms for Dongkui waxberry, carried out experimental research and extension of single-tree insect-proof net room cultivation techniques, and achieved remarkable results. The demonstration and application of this technique are briefly introduced as follows.
1 Research, development and extension of insect-proof net room cultivation techniques for Dongkui waxberry in Huangyan
The ripening period of Dongkui waxberry coincides with the plum rain season of high humidity and high temperature, when the fruit is susceptible to fruit fly damage. In production, spraying pesticides to control insects is not effective and seriously affects the quality and safety of waxberry fruit. Under the technical guidance of experts from the Zhejiang Academy of Agricultural Sciences, the Zhejiang Provincial Department of Agriculture, and the Taizhou Municipal Agriculture Bureau, in May 2010, a fruit fly sterilization experiment on Dongkui waxberry was carried out in a waxberry orchard in Zhantang Village, Yuanqiao Town, and 18 single-tree insect-proof net rooms were erected, blocking the occurrence and damage of waxberry fruit flies; at the same time, the waxberry fruit quality and taste were relatively good, and the picking time was extended. In 2011, the fruit tree technical expert team of Huangyan District took the lead domestically in innovating the insect-proof net room cultivation technique for Dongkui waxberry, selected 8 waxberry bases to carry out experimental demonstration of the technique, and built more than 600 single-tree insect-proof net rooms; in 2012, the technique was demonstrated, promoted and applied throughout the district, and more than 10,000 single-tree insect-proof net rooms were built. Application results showed that insect-proof net room cultivation ensured high-quality and safe fruit, and also brought a good price: the orchard-gate selling price of waxberry fruit grown under insect-proof net rooms was more than 30 yuan/kg higher than that of conventional fruit of the same grade. The promotion and application of this technique was affirmed by leaders and experts. On June 28, 2012, the Zhejiang Provincial On-site Meeting on Waxberry Quality and Safety Technology was held in Huangyan, and single-tree insect-proof net room cultivation technology was listed as a main promoted technology for waxberry quality and safety production in the province. After 2013, Huangyan District further increased policy support for this technique, changed the moso bamboo supports to galvanized steel pipes, and raised the subsidy for each insect-proof net room to 300 yuan. At the same time, it continued to advance technological innovation. In 2014, a film-mulching rain-shelter experiment was carried out on the basis of insect-proof net room cultivation. On June 22, 2016, the provincial on-site observation meeting on rain-shelter cultivation of waxberry was held in Huangyan. In 2017, the technique of insect-proof net room + film mulching rain shelter had become a main promoted technique in Dongkui waxberry production in Huangyan. The district promoted and applied insect-proof net room cultivation on 56,000 trees,with an economic benefit of 25,000 yuan per 667 sq m. In addition to large-scale promotion and application in Huangyan, insect-proof net room cultivation also spread to other waxberry-producing areas in the province, including other cities (counties) and districts in Taizhou, Wenzhou, Lishui, Jinhua, and Ningbo, effectively promoting the development of the waxberry industry and increasing farmers' income, with increased economic and social benefits [Jishan Huayao].
2 Results of promoting insect-proof net cultivation
2.1 Effectively blocking fruit fly damage
When the insect-proof net room cultivation technique is applied to Dongkui waxberry, the insect-proof net blocks most pest invasion and effectively blocks fruit fly occurrence and damage. According to experimental surveys, the relative control effect of net room cultivation on waxberry fruit flies was more than 98%. In the late harvest period, the fruit fly infestation rate of fruit was below 6%, while in the control area the fruit fly infestation rate of fruit was above 88%.
2.2 Creating a good ecological environment, with high waxberry yield and
better fruit flavor
The net room cultivation technique for Dongkui waxberry has an environmental regulating effect, creating a good micro-environment for waxberry growth, significantly weakening heavy rain and strong wind, avoiding dust pollution, reducing fruit drop during the ripening period, helping the waxberry fruit fully ripen, increasing the rate of marketable fruit, and giving fruit with a clean surface, no insect damage, and no contaminants, with plump and well-developed flesh columns and better fruit flavor and taste. According to surveys, on hot sunny days the maximum temperature inside the net room was 5°C lower than in the control area, while maintaining relatively high humidity. According to surveys of the experimental area, after waxberry adopted net room cultivation, the adverse effects of high temperature and rainy weather on waxberry fruit growth were reduced, fruit drop and rotten fruit during the ripening period were reduced, the marketable fruit rate increased from 40% to 92%, the proportion of high-quality fruit increased from 40% to 68%, the fruit drop rate decreased from 23% to 3%, and yield increased by 20%. The fruit also had bright color, tender and juicy flesh, and a richer flavor.
2.3 Extending the fruit harvest period and achieving a high selling price
When the net room cultivation technique is adopted for Dongkui waxberry, the fruit ripening period is delayed by 3-5 d, meaning the harvest time is extended by up to 5 d. In particular, when the net room cultivation technique for Dongkui waxberry is promoted and applied on a large scale in high-mountain areas, the harvest period is extended from around July 10 to around July 15, lengthening the market supply period for fresh Dongkui waxberry. In the later period, the quantity of Dongkui waxberry fruit is not large, and because the temperature is relatively high and market demand for fresh waxberry is large, the selling price is correspondingly higher, and the improvement in market competitiveness and increase in economic benefits are more significant. In July 2017, the orchard-gate selling price of high-quality Dongkui waxberry grown under net rooms was more than 60 yuan/kg, more than 30 yuan/kg higher than that of high-quality fruit harvested conventionally in the same period. For example, in the high-altitude area, the 900 Dongkui waxberry trees of the Lianyi Chen Family Farm adopted net room cultivation technology, with harvesting starting on July 2 and ending on July 20; the Dongkui waxberry was in short supply on the market, selling for as high as 140 yuan/kg and at least 80 yuan/kg.
2.4 Reducing pesticide residues and ensuring fruit quality and safety
In traditional waxberry cultivation, chemical agents must be applied during production to control pests and diseases such as fruit flies, seriously affecting the quality and safety of waxberry fruit. Applying net room cultivation technology changes farmers' blind use of pesticides and nutrient solutions, achieves no pesticide or nutrient solution use during the fruit ripening period, and ensures fruit quality and safety. According to random sampling of products each year by provincial, municipal, and district agricultural product quality and safety testing units at Dongkui waxberry bases under net room cultivation, all test results met the requirements and reached green food standards.
3 Main cultivation techniques for insect-proof net cultivation
3.1 Net room cultivation method
The single-tree net room cultivation method is adopted. For net room construction in production, it is advisable to choose orchards on gentle slopes and avoid sites at strong wind openings, and to choose Dongkui waxberry trees with a relatively high level of management, strong tree vigor, and normal fruiting; generally, each Dongkui waxberry tree is required to bear more than 30 kg of fruit. Through the application of pruning techniques to Dongkui waxberry trees, the canopy height is controlled below 3.5 m, with good ventilation and light transmission and evenly distributed branches. If a waxberry tree bears too much fruit, thinning must also be done well to retain a reasonable fruit load.
3.2 Preparation for net room construction
Preparation of net room construction materials. Steel pipes, moso bamboo strips, wooden stakes, insect-proof net, zippers, plastic rope or cloth strips, agricultural film, etc. For the net room facility, hot-dip galvanized steel pipes are best; for the insect-proof net, 40-mesh nylon net is preferable, and net tents of different specifications should be made according to the size of the waxberry canopy. The net room is built with 8 hot-dip galvanized steel pipes, with insect-proof net fitted around the sides, and the top of the shed surface should be more than 80 cm above the top of the tree. For the rain-shelter agricultural film, transparent agricultural film or rainproof cloth with a thickness of 0.11 mm or more is preferable.
3.3 Time for covering net and film in net room cultivation
For net room cultivation time, generally the insect-proof net is covered 40-50 d before waxberry harvest (before waxberry fruit flies enter the orchard to cause damage). The net must not be covered too late; otherwise, it is difficult to control invasion and damage by pests such as fruit flies. In the Huangyan production area, this is in early to mid-May, when insect-proof net tents of the corresponding specifications are selected for full-tree coverage of individual trees. When covering the insect-proof net tent, a certain space should be kept between the insect-proof net and the waxberry branches and shoots. If the frame is not spacious enough and the insect-proof net presses tightly against the waxberry branches and shoots, remedial measures should be taken; otherwise, fruit rot and insect damage will occur. Small bamboo poles should be used to push the insect-proof net outward so that the insect-proof net is 20 cm away from the waxberry branches and leaves. At the same time, carefully check whether the bottom edges around the net tent are compacted and whether the zipper openings are completely closed, ensuring that the entire insect-proof net tent does not allow pests to enter and exit freely. For film covering time, generally 10 d before harvest, cover the top with special plastic film with good light transmission for rain shelter, and remove it promptly after harvest ends.
3.4 Net room management
After the insect-proof net is covered over the net room, daily management should be strengthened. The orchard should stop using all pesticides and nutrient solutions until the net is removed after waxberry harvest is completed. Frequent inspections should also be carried out to check whether the net room is intact, ensuring the insect-proof net is sealed; the bottom of the net should be compacted with soil, and the pressure lines on the top of the shed should be tightened. In particular, pay attention to damage to the net room after strong wind and rainfall; if strong wind easily lifts the net tent or tilts the net frame, timely repair and reinforcement should be carried out, otherwise all previous efforts will be wasted. Fallen fruit should be cleaned up promptly and buried deeply in a centralized manner to reduce pest sources. During waxberry fruit harvest, personnel entering and leaving should promptly close the zipper of the insect-proof net tent to prevent invasion and damage by pests such as fruit flies. After waxberry harvest ends, remove the net tent, clean and store it for use next year. Also promptly carry out post-harvest cultivation management such as fertilization and pruning of waxberry trees to ensure a bumper harvest next year.
4 Suggestions for the development of insect-proof net cultivation
Although insect-proof net room cultivation of waxberry has been promoted and applied on a large scale in Huangyan with remarkable results, there are also some shortcomings in the implementation of insect-proof net room cultivation, such as the relatively small space of a single-tree insect-proof net room, poor ventilation and air permeability, and excessive humidity when continuous rainy weather occurs during the fruit ripening period, making fruit susceptible to diseases such as white rot and causing fruit drop and yield losses. The selected frame types also need gradual improvement to further enhance wind and rain resistance; and more scientific and reasonable technical support is needed in cultivation. Specific suggestions are as follows.
4.1 Increase experimentation and research on insect-proof net room cultivation techniques for waxberry
The insect-proof net room cultivation technique for waxberry is not yet perfect. According to the site conditions and growth requirements of waxberry cultivation, the net room structures for single-tree, two-tree, and multi-tree systems should be scientifically designed, facility materials and frame types should be reasonably selected, indoor ventilation conditions should be improved, and the wind resistance and rain shelter capacity of the net room should be enhanced. At the same time, research should focus on fertilization, pruning, pest and disease control, net covering time, temperature and humidity regulation, and film mulching for rain shelter in insect-proof net room cultivation of waxberry, and a set of standardized techniques for insect-proof net room cultivation of waxberry should be summarized.
4.2 Vigorously train and promote insect-proof net room cultivation techniques for waxberry
The insect-proof net room cultivation technique for waxberry is an innovative technique and requires even more government policy and funding support. Agricultural technicians at all levels should go deep into the grassroots, vigorously publicize the superior performance of insect-proof net room cultivation, carry out technical training, and establish demonstration orchards to promote the demonstration and extension of insect-proof net room cultivation techniques for waxberry.
4.3 Strengthen publicity and promotion of the net room waxberry brand
Promote and apply the insect-proof net room cultivation technique, achieve no pesticide use during the waxberry fruit ripening process, ensure fruit quality and safety, and produce fruit of good quality. In order for consumers to eat safe and high-quality waxberry fruit, the government should increase investment and strengthen publicity and promotion of net room waxberry. All localities should organize farmers practicing insect-proof net room cultivation of waxberry to establish cooperative alliances, implement unified operation techniques, unified fruit quality, and unified packaging labels, build a net room waxberry brand, and increase economic benefits.