The main pest control technology of pecan in the United States

The main pest control technology of pecan in the United States

1 The main disease of pecan in the United States and its control methods

There are many diseases of pecans in the United States, and frequent diseases have become one of the important factors restricting the large-scale development of pecans in the United States. Juyunwei and others summarized 21 diseases of Pecans in the United States, including 16 fungal diseases, 3 bacterial diseases, and 2 nematode diseases. On the basis of the forest stand survey, the author summarizes and sorts out the five diseases that harm the American pecan, describes its symptoms and proposes corresponding prevention and control measures.

1. 1 Sores dementia

Dementia is a fungal disease that affects leaves and fruits and occurs frequently in humid climates. The symptoms of the disease are: the leaves or green fruits of the disease initially appear black, round and small dots, and as the disease develops, the scattered dots gradually merge into contiguous black spots. And eventually leads to leaf fall and fruit fall.

Measures for the prevention and treatment of pecan dementia in the United States: Anti-ulcer dementia breeding is one of the important contents of the breeding of pecan varieties in the United States. The anti-ulcer carbuncle ability varies significantly between the varieties. It is recommended to choose varieties with strong disease resistance. At the same time, the following garden management measures are very effective in the prevention and treatment of sore disease: excavation of drainage ditches. Prevent water accumulation; Transplant over-dense plants, prune over-dense branches, and enhance the ventilation and light transmission ability of orchards; In winter, diseased branches are cleaned up and burned or buried deep in the orchard. Pay close attention to the occurrence of orchard diseases, in the early stage of the disease, the use of fungal fungicides sprayed every 2 weeks, can effectively reduce the harm of sores and diseases.

1.2 Leaf rotunda disease

Leaf rotifer disease mainly occurs in the leaves, the symptoms are: at first on the leaf tip or leaf margin appear yellow-green small spots, small spots are then connected into pieces, expanded into brown spots, the center of the spots is a ring (concentric ring). Causes severe leaf fall. Rotifers multiply in the form of brachiophores and spread with rainwater, and the disease can occur every year in orchards once it encounters high temperature and humidity.

American pecan leaf rotifer disease prevention and control measures: it is recommended to focus on prevention, timely drainage after rain, to prevent moisture retention, can reduce the incidence of disease. Spraying with phenylmycin 600-1000 times liquid before the onset of the disease can play a better control effect. After entering the onset period, spray every 10 days with 600 to 800 times liquid of Bacteriocinalis Qing wettable powder. Continuous spraying 3 times can effectively control the harm of rotifer disease.

1.3 Ulcer disease

The onset of ulcer disease is generally in early spring or summer and autumn. Mainly harmful to tree trunks. Symptoms: the bark of the affected part is cracked or even shed, and there are often water-stained spots in the affected area. The spots will gradually enlarge and then sink into dehydration. There are black or brown fruiting bodies. When the trunk is seriously damaged, it affects the delivery of nutrients and causes the tree to weaken. When the damage is severe, it can lead to the death of the whole plant.

Measures to control hickory canker disease in the United States: when managing in the garden. Drainage ditches are to be excavated. Prevents the root system from accumulating water for a long time; Timely fertilization to ensure tree nutrition. Maintaining strong growth potential energy effectively reduces the risk of disease; In winter and summer, the trunk should be whitened to prevent frost damage and sunburn. In the early stage of the disease, the ulcer surface is wrapped with mud and sealed with a film for more than 2 months, and the cure rate is high.

1.4 Arbuscular disease

American pecan tuft disease belongs to the phytoplasma disease, and the growth of the plant after the disease is weak. Nut yield and quality will be greatly reduced. Symptoms of the disease are: the lateral buds on the diseased branches are abnormally developed, the branches are long and thin, and they are clumpy, and the leaves are larger and softer than normal leaves. According to the degree of infection, it is divided into: whole plant infection and partial branch infection. The disease occurs more often in the spring, and the disease-susceptible branches germinate 7-10d earlier than normal branches. The source of infection is mostly the original infected plant, and the pathogen is transmitted through the feeding of insects such as leafhoppers between the diseased and healthy plants.

Control measures for Hickory tuft disease in the United States: The disease is a typical plant systemic disease. There is currently no effective chemical agent for the prevention and treatment of the disease; If some of the branches are infected with the disease, it is recommended to prune, if the whole plant is infected, the diseased plant must be removed and destroyed away from the orchard.

1.5 Zinc deficiency

Zinc deficiency is a non-contagious disease. Ensuring that the soil contains sufficient zinc is one of the prerequisites for high yields of Pecans in the United States. Zinc deficiency is predisposed to soils with low alkaline or zinc content. Symptoms of zinc deficiency: the upper leaves of the branches are lotus-like. Bright leaves. The leaves are small and brittle. The internodes are short, the germination rate is high, and the branching force is weak.

Measures to control zinc deficiency in pecans in the United States: improving soil structure. Increase the application of organic fertilizers to improve the soil's ability to supply zinc; Increasing the application of zinc sulfate in winter can effectively improve soil conditions and reduce the symptoms of zinc deficiency; Foliar spraying with a mass fraction of 0.4% zinc sulfate is more effective in summer.

2 The main pest of pecans in the United States and their control methods

At present, insect pests have occurred frequently in American hickory orchards throughout the country, and the harm is serious. According to foreign data, there are more than 270 kinds of pests in the United States pecan, combined with foreign research progress, on the basis of the American pecan forest stand survey, we believe that there are mainly 13 kinds of pests that are more harmful to the American pecan pecan, involving 13 species of 3 orders and 8 families.

2.1 Hemiptera

2.1.1 Aphids

There are two main species of aphids that harm American pecans: black aphid and yellow aphid.

Black aphids nibble on the leaves and release toxins. After nibbling, a yellow lump will appear and will eventually fall off, and black aphid nibbling will cause early leaf fall and affect nut production. At the same time, premature leaf shedding not only affects the yield of the current year but also has a significant impact on the yield of the second year.

Yellow aphid hazard characteristics are obvious. Usually, after nibbling, it leaves mucus in the leaves, which breeds coal-stained fungal hyphae, and mycelium obscuring the leaves reduces the leaf photosynthetic capacity. When the astragalus is seriously harmful, it will damage the tree vascular system. Affects chlorophyll synthesis and leaf development.

American pecan aphid control measures: protect the natural enemies of aphids such as red spiders and heterochromatic ladybirds; At the same time, in winter, 2 and a half garden rings are scraped in the lower part of the trunk, staggered up and down, one on one side; The depth of the scraping skin should be to scrape the green cortex layer. Width 10-15 cm. Apply 40% of the Leguo emulsion to the scraper, the control effect is particularly good. Spray with 1000 times imidacloprid solution at the beginning of the occurrence of insect pests. The control rate can reach 82%. Repeat 1 spray after 1 month. The effect is better. Control 3-4 times a year, basically control the damage of aphids.

2. 1. 2 Aphids

It is mainly a leaf gall type rhizophrod, and seedlings and young trees are more susceptible than adult trees. Leaf gall type rhizobia aphid occurs once a generation per year. Overwintering eggs hatch in early April, and if the aphids nibble on the leaves and form galls on the leaf surface, the phylloxera sucks nutrients and lays eggs in the gall. Gall greatly reduces the photosynthetic area of leaves, affects tree growth, and causes a large number of leaves to fall when the damage is serious.

Measures for the prevention and control of Hickory H. Phylloxera in the United States: in winter, the trunk is coated with a 3-5 degree Baume stone sulfur compound of 3-5 degrees; Summer with 2. 5% cyanothematis emulsion 3000 times liquid or 80% dichlorvos emulsion 1000 times liquid sprayed on the whole plant, with good control effect.

2.2 Lepidoptera

2.2.1 Stinging moths

There are three main species of thorn moths: yellow thorn moth, double-toothed green thorn moth and brown thorn moth. The larvae of the stinging moth nibble on the leaves, resulting in the absence of leaf segments or even only the petiole and main vein, which has a significant impact on the growth of the tree body; The thorn moth erupts in May and July, which is a critical period for the fruit setting of long pecans, and the leaves are damaged. Insufficient photosynthetic capacity. Young fruits without enough nutrients will fall off in large quantities, which will obviously affect the yield of the year.

American pecan prickly moth control measures: From June to July every year, when the first generation of larvae are in full bloom, the dimethoder sprayed with 1000 times the liquid is very effective. In winter, it is necessary to combine the qingyuan to remove the insect cocoons on the branches and leaves. Elimination of overwintering cocoons; Other than that. The cocoon of the brown thorn moth is in the soil near the trunk, which can be excavated and burned centrally; Booby-trapping with lights in summer can also play a better prevention and control effect.

2.2.2 Leafminer moth

Leafminer moth larvae mainly harm American pecan fruit. Especially in the early stage of fruit set, it will lead to a large number of fruit drops. Leafminer moths survive winter in the form of overwintering cocoons. It begins to move after the tree body germinates, and the young shoots are the first to be harmed; Eggs are laid in May and June, and after the eggs hatch, they begin to nibble on the green fruit, and the larvae will move between the fruits. There are distinct filaments at the bottom of the fruit for easy identification. Leafminer larvae are extremely harmful to the fruit, and one larvae is enough to destroy the entire fruit cluster.

Control measures of Hickory leafminer moth in the United States: Winter combined with garden management. Remove and burn dead branches and leaves; When there are larval infestations in the spring, chemical insecticides are sprayed to kill the adult and hatching larvae of leafminer moths; An additional dose of the systemic insecticide is applied between May and July. It can effectively reduce the harm of leafminer moths.

2. 2. 3 wood stupid moths

Wood folly moth larvae after hatching. Moths feed on the phloem and forming layers under the skin, often causing the bark to peel off; After eating the xylem, it chisels the irregular worm path upwards and downwards, destroying the transporting tissue, causing the tree to weaken, the branches to wither and even die.

Control measures for the American pecan wood folly moth: coat the trunk with stone sulfur compound to prevent adults from laying eggs on the trunk; Clean up sick and dead branches in time. Eliminate insect sources; Utilizing the phototropism of adults. Booby traps using lights; During the adult stage, spraying 50% octyl thiophos emulsion 1500 times liquid can play a good control effect.

2. 2. 4 feet of midge

Occurs in both spring and autumn and is one of the main pests of the leaves. The larvae are a gluttonous pest that often conglomerates as pests, especially when the population density is large. It can eat the leaves clean in a very short period of time, which seriously affects the growth of the tree.

American pecan inchworm control measures: digging up overwintering pupae in the winter; Use of the phototropism of adult insects to use light booby traps; furthermore. Spraying 90% of the dichlorvos or 80% of the dichlorvos 800-1200 times the liquid at the larval stage can play a good control effect.

2.3 Patina Golden Turtle

There are many species of scarab beetles that harm American pecans, mainly the aeruginosa golden turtle. The larvae grub is a common underground pest that primarily harms the roots of American pecans. Adults nibble on leaves, shoots or young fruits. The adult uses the horns of the head to burrow into the peel and nibble on the flesh, causing the fruit to fall.

American pecan aeruginosa turtle control measures: stir 50% octyl thiophosphorus emulsion 100 g with 1kg slag, and sprinkle the made poisonous sand into the sowing ditch with the seed to poison and kill the larvae; Spray foliage with 0.4% dichlorocytes at the height of the hazard or use the pseudo-death of adults to beat the tremors in the evening. Collect and destroy them intensively, and use lights to booby trap them at night. It can effectively reduce the harm of scarab beetles.

2.4 day cattle

The pests of the family Tianniu that harm American pecans are mainly star-spotted tianniu, cloud-spotted tianniu and thin-winged sawn tianniu. Tengu generally occurs in 1-2 years for 1 generation. The larvae overwinter in the xylem, and the larva matures as pupae at the end of the moth tunnel. The feathered adult bites through the cortex and drills out. Adults begin to appear in late April, june to July, and August is the woody part of the end larvae that feed on branches, stems and roots. There is brown feces and coarse wood chips discharged from the affected area, and the tree weakens after the tree is damaged, and when it is severe, it will die; Adults bite the veins, young branches and young bark of the long pecan, blocking the delivery of water and nutrients to the tree, which can cause the entire plant to die in severe cases.

American pecan Tianniu control measures: artificial hunting or booby-trapping of Tianniu adults with black light lamps, and the application of Tianniu Weilei 800-1000 times liquid in the peak of adult occurrence can effectively reduce the harm of Tianniu; In addition, in May and August, it is necessary to frequently check whether there is feces excreted from the trunk, and once it is found that there is a fecal opening, immediately use a cotton swab dipped in pesticides such as oxidized Leguo into the punching hole, or inject 40% Leguo emulsion 25 times liquid into the worm hole with a syringe, and then seal the worm hole with mud to kill the larvae.