Application Methods and Technical Key Points of Fruit Tree Bird-Proof Nets
At present, more than 98% of orchards suffer from bird damage, and the annual economic losses caused by bird damage amount to as much as 700 million yuan. Through years of research, scientists have found that birds have a certain sensitivity to color, especially to blue, orange-red and yellow. For this reason, on the basis of this research, researchers invented a mesh net made with polyethylene as the basic material to cover the entire orchard, and used it for apples, grapes, peaches, pears, cherries and other fruits, achieving very good results.
I. Color selection. It is generally recommended to use yellow bird-proof nets in mountainous areas and blue and orange-red bird-proof nets in plains. Birds dare not approach the above hues, which can both prevent birds from pecking at the fruit and keep birds from hitting the net, with an obvious bird-proof effect. In production, it is recommended not to use transparent mesh nets, as such nets have no repellent effect and birds easily hit the net.
II. Selection of mesh size and net length. This depends on the size of local birds. If small birds such as sparrows are the main species, bird-proof nets with a 3 cm mesh size can be selected; if larger birds such as magpies and turtledoves are the main species, bird-proof nets with a 4.5 cm mesh size can be selected. For bird-proof nets, a wire diameter of 0.25 mm is generally sufficient. The net length should be purchased according to the actual size of the orchard. Most net products on the market are 100-150 m long and about 25 m wide, and it is best to cover the entire orchard.
III. Selection of support height and density. When installing fruit tree bird-proof nets, supports must first be laid. Finished supports can be purchased, or they can be welded from galvanized pipes, angle iron, etc. The part buried underground should have a cross piece welded on to resist lodging. Iron rings are welded to the top of each support, and wire is threaded through to connect the supports. After the supports are laid, they should be firm and durable, and the height should be about 1.5 m higher than the fruit tree height to facilitate ventilation and light transmission. The support density is generally 5 m in length and 5 m in width. The support density can be increased or decreased appropriately depending on the planting spacing between plants and rows and the size of the orchard. The denser the supports, the better the effect, but the denser they are, the higher the cost. Bird-proof nets of the corresponding width can be purchased according to the width to save materials.
IV. Installation of top nets and side nets. Fruit tree bird-proof nets should be installed in three dimensions. The net above the canopy is called the top net. The top net is threaded onto the wire stretched at the top of the supports, and care should be taken that the joints are tight with no gaps. The net on the outer side of the canopy is called the side net. The joints of the side net should be tight, and its length should reach the ground with no gaps. The top net and side net should fit closely together to prevent birds from getting into the orchard and causing damage.
V. Determination of installation time. Fruit tree bird-proof nets are only used to prevent birds from damaging fruit. Generally, the fruit tree bird-proof nets are installed 7-10 days before the fruit ripens, when birds begin to peck and cause damage. After the fruit is completely harvested, they can be removed and stored to prevent aging from exposure in the field, which would affect their service life.
VI. Maintenance and storage of fruit tree bird-proof nets. After installation, check the fruit tree bird-proof nets at any time, and repair any damage promptly. After the fruit is harvested, carefully remove the fruit tree bird-proof nets, roll them up, pack them, and store them in a cool, dry place for use again when the fruit ripens the following year. They can generally be used for 3-5 years.?
Ma Wenhui, Shijiazhuang Fruit Tree Research Institute, Hebei Academy of Agriculture and Forestry Sciences