Control of snow blight of spruce

Snow blight harms spruce needles, which are reddish brown. Snow blight occurs under snow. Ascospores invade spruce needles covered with snow. After maturing from September to October every year, it spreads with the help of wind and Rain Water. It was observed that in the young forest after artificial reforestation, because of the high planting density in the past, the situation of "hand in hand" was formed. once the disease spread particularly seriously, 1/2 of the needles of the plant were infected and lost green and turned reddish brown, resulting in the death of the whole plant. The unclosed regeneration land of Tex Forest Farm is nearly 2666 hectares. in order to ensure the artificial renewal of afforestation results over the years and make young trees become forests as soon as possible, we have adopted a variety of control methods, and achieved certain results. The measures taken in the prevention and control process are briefly introduced as follows:

I. Forest management measures

1. Interplant

After melting snow and freezing every year, the young trees that form "hand in hand" are interplanted to increase the nutrition space and improve their disease resistance.

two。 Pruning

Before the bud of the young tree opens, cut off the susceptible branches and burn them centrally. The susceptible site generally spreads from the bottom up, cutting off all the susceptible branches and keeping the distance between the lowest branch and the ground at 1/3 of the tree height after cutting, which eliminates the source of the disease on the one hand and reduces the probability of infection on the other.

II. Chemical control

1. Prevention and control time

Chemical control is carried out when the ascospores mature and begin to spread from September to October every year.

2, fungicides

Use carbendazim 25,50% wettable powder, methyl topiramate 50% wettable powder, concentration ratio 1 ∶ 400.

3. Spraying machine

Due to the limitation of the terrain, only the mobile spray sprayer, WFB- 18, is used, which has all the functions of renewing the land in the mountain area.

4. Direction, spray direction and wind direction

Combined with the terrain, spray from upwind to downwind.

III. Summary

The combination of interplant, pruning and chemical control is the best to control spruce snow blight. Due to the limitation of water source and topography, some diseased plots can not take chemical control, and the method of pruning twice in three years, once in the first and third years, can also achieve the desired results. If the tree is as high as 3 meters high, the disease resistance will be enhanced, and the phenomenon of death caused by disease will not occur.