1 peach tree leaf disease
1.1 symptoms
When the spring leaves are just taken out from the bud scales, the symptoms appear. At the beginning of the disease, the diseased leaves become thick and swollen, and they are curled and deformed.
The color is red; as the diseased leaves gradually unfold, the degree of curling and shrinking is also aggravated, causing the whole leaves to have corrugated irregularities, and in severe cases the leaves are completely deformed. The diseased leaves are obviously swollen and thick, and the texture becomes brittle.
It is light yellow to reddish brown; in the late spring and early summer, the surface of the diseased leaf produces a grayish white powder.
It is the ascospore layer of the germ.
Finally, the diseased leaves become brown, dry, and fall off. After the leaves are fallen, the new leaves extracted by the axillary buds are no longer affected. After the young shoots are damaged, the diseased shoots are grayish green or yellow, which is shorter and slightly thicker than the normal branches.
The leaves are clumped, and the severely affected ones often die. Flowers and young fruits are damaged, the petals are enlarged and long, mostly fall off; the diseased fruit that has not fallen off, uneven development, blocky ridges, yellow to reddish brown,
The fruit is often cracked. The flower is damaged and the fruit is easy to fall off.
1.2 pathogens and pathogenesis
The pathogen is ascomycetes, which mainly damages the leaves and can also harm young shoots, flowers and young fruits. The pathogens are overwintered by ascospores or spores in the bud scales or bud scales. When the peach buds germinated in the spring of the next year, the spores germinated directly from the epidermis or stomata of the leaves, damaging the young leaves or new shoots. After the invasion of the pathogen, the diseased leaves are swollen and shrunk. Later, a sub-capsule layer is formed between the stratum corneum of the diseased leaf and the epithelial cells.
Reproduction of ascospores and spores. In summer, when the temperature is high, it is in the bud scale or the bud scale gap in summer, and even winter. The occurrence of peach leaf shrinkage is closely related to the early spring climate. In early spring, when the peach buds sprout, the temperature is low (10 °C ~ 16 °C), the duration is long, the humidity is high, and the disease occurs seriously; when the temperature is above 21 °C, the disease stops developing. In areas or years where the early spring is cold and rainy, the incidence of peach leaf shrinkage is heavier; in early spring, the mild and dry disease is milder. Diseases generally range from 4
It began to occur in the first half of the month, and it was the peak period from the end of April to the beginning of May. After the temperature increased in June, the onset gradually stopped.
1.3 Control measures
1.3.1 Agricultural control
When planting a new Taoyuan, it is recommended to plant varieties that are both high-yield, high-quality and disease-resistant; strengthen orchard management, enhance tree potential, and improve disease resistance. In the late fall or early spring, timely remove the diseased foliage, remove the diseased body, burn it centrally or bury it deeply to reduce the source of the disease. For the peach plantation with heavier incidence, it is necessary to replenish fertilizer and watering in time to enhance the tree potential and improve disease resistance as soon as possible.
1.3.2 Chemical control
In the dormant season, spray 3~5 Baumeite sulphur mixture to eradicate the pathogen of wintering; in the period from flower bud to petal red, the tree is sprayed once with 2~3 Baume's stone sulphur or 1:1:100
Bordeaux mixture, eliminate wintering bacteria on trees; after Xiehua, spray 70% thiophanate-methyl WP 700 times or 50% carbendazim WP 600 every 10 days
Double liquid, 70% mancozeb wettable powder 500-600 times liquid.
2 peach tree fungal perforation
2.1 symptoms
After the leaf is infected, the leaf surface appears nearly round or irregular purple to brown lesions, diameter 2 ~ 6
Mm. When the humidity is high, the black back of the leaf back grows, that is, the pathogen fruit body. After the diseased leaves have fallen off, the perforations remain on the leaves. After flowering and fruit infection, the lesions are small and round, purple, and rough after bulging. After the peduncle is infected, it will dry out without flowering. When the new shoots are onset, dark brown spots with red edges appear, and there is fluid on the surface. After the older branches are infected, they form a spherical tumor, accounting for 1/4 to 3/4 of the area around the branches.
2.2 pathogens and pathogenesis
The pathogens of the genus Mortierella and the genus Cercospora are all fungi. Mainly harmful to leaves, flowers and branches. Both of these pathogens are overwintered by mycelium in diseased leaves or branch disease tissues. The temperature in Hunchun rises and the conidia are produced after rainfall. It spreads through wind and rain, infects leaves, new shoots and fruits, and is later produced by the diseased part. Conidia can be reinfected. The development temperature of the bacteria is 7 ° C ~ 37 ° C, and the suitable temperature is 25 ° C ~ 28 ° C. Low temperature and rain are good for disease occurrence and epidemic.
2.3 Prevention measures
2.3.1 Agricultural control
Strengthen the management of Taoyuan. For the peach orchard with high groundwater level or soil viscosity, it is necessary to improve the soil and drain it in time; rationally trim and trim, remove the dense branches, drooping branches, and mooring branches to make the ventilation and light transmission good, reduce the temperature and humidity of the orchard; Organic fertilizers, avoid partial application of nitrogen fertilizer, promote the growth of the tree body, improve disease resistance; combine winter shears, timely cut off diseased branches, completely remove diseased leaves, concentrate burning or deep burial, reduce the source of overwintering bacteria.
2.3.2 Chemical control
After falling flowers, spray 70% mancozeb WP 500 times or 75% chlorothalonil WP 700-800 times solution, 70% thiophanate-methyl WP 1 000 times, every 10~15 d Spray once.
3 Peach tree bacterial perforation
3.1 symptoms
After the onset of the leaves, there are purple-brown to dark brown round or irregular shaped lesions with a diameter of about 2
Mm, water-stained yellow-green halo around the lesion, and finally the lesions are dry, shed to form perforations, and sometimes several lesions are connected to form large perforations. At the beginning of the fruit, the brown spotted small round spot is enlarged, and then becomes dark purple. The center is slightly sunken and the edge is watery. When the weather is wet, yellow-white sticky secretions often appear on the lesions, and cracks occur when dry. The disease develops lesions on the branches. Spring ulcer plaques occur on shoots that have been infested during the summer of the previous year. Spring 1st
When the new leaves appear, the branches can form 1~10cm long and the width does not exceed 1/2 of the diameter of the branches.
Ulcer lesions can sometimes cause dry shoots. Most of the summer ulcer spots occur on the young shoots of the year, producing round or oval, water-stained, purple-brown, and slightly depressed ulcer spots in the center.
3.2 pathogens and pathogenesis
The pathogen is Xanthomonas, which mainly damages leaves and also harms fruits and shoots. The pathogens overwinter in the cortical tissue of the branches. In the spring, the bacteria began to move with the temperature rising, forming spring ulcer spots and becoming the main source of primary infection. Before and after the peach tree blooms, the bacteria overflow from the diseased tissue, spread by wind and rain or insects, and invade through the stomata of the leaves, the bud marks of the branches and the lenticels of the fruit. The optimal temperature for pathogen development is 24 ° C ~ 28 ° C, the highest is 37 ° C. Leaf fruit is generally 5
Onset during the month. In the summer drought, the disease progresses slowly, and in the autumn, it will infect later.
3.3 Control measures
3.3.1 Agricultural control
Select resistant varieties; strengthen the management of peach gardens, increase the application of organic fertilizer; scientific plastic trimming, reasonable irrigation, good ventilation and light transmission; cut off diseased branches in winter and spring, thoroughly remove diseased leaves, concentrate burning or deep burial, reduce overwintering bacteria sources .
3.3.2 Chemical control
Spray 4~5 Baumeite sulphur mixture or 45% crystal sulphur mixture 30 times solution, 1:1:100 Bordeaux solution before germination in early spring; spray 5% toxic water clearing agent 200~300 times liquid or 72% agricultural use after germination Streptomycin wettable powder 3000 times solution, streptomycin sulfate 4000 times solution.
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