This paper explains in detail the control methods of root rot and stem rot of ginkgo biloba seedlings.

Root rot and stem rot of ginkgo biloba seedlings often occur in 1-2-year-old ginkgo seedlings, especially one-year-old seedlings, which often cause a large number of seedling death. So what are the control methods of ginkgo seedling root rot and stem rot?

Symptoms of root rot and stem rot of ginkgo biloba seedlings

1. Root rot of ginkgo biloba seedlings

Root rot is caused by cortical rot in the early stage and damage to xylem in the later stage. Many pathogens can cause root rot, and the symptoms of root rot caused by different pathogens are different. The main pathogens causing root rot are Armillaria mellea and Phytophthora.

(1) symptoms of root rot caused by Armillaria mellea.

Dark brown watery spots appeared in the rhizome cortex at the initial stage of the disease. after the gradual expansion, the cortex of the root blackened, the phloem was very easy to fall off, the xylem became brown and rotten, and accompanied by the smell of lees.

In the later stage of the disease, the disease spot spread downward and the whole root system rotted. When the soil environment is moist, the disease tissue is full of white to yellowish fan-shaped mycelium, which can emit blue-green fluorescence in the dark environment. In the later stage, there are sometimes clusters of honey-yellow umbrella-shaped basidiocarps on the diseased roots. The aboveground leaves turn yellow and fall off, some of the branches are dry, or the whole plant wilts and dies.

(2) symptoms of root rot caused by Phytophthora.

At the beginning, the pathogen invaded from the root tip or rhizome, and then gradually spread to the interior. At the initial stage of the disease, the growth of the aboveground leaves weakened, yellowed, curled and became smaller, the root system grew weak when the disease was mild, and the main root cortex rotted in severe cases. Seriously, the early defoliation began in July, and all the leaves of individual plants fell off in August, and even the whole plant withered. Old trees are more likely to occur than young ones.

2. Stem rot of ginkgo biloba seedlings.

In the early stage of stem rot, the seedling base turned brown, the leaves lost normal green, and drooped slightly, but did not fall off. The susceptible site rapidly expanded upward, so that the whole plant withered. The basal cortex of the diseased seedling was shrunk, and the intradermal tissue was spongy or powdery, with many small black sclerotia.

The pathogen can also invade the xylem of seedlings, so small sclerotia can sometimes be seen in the brown hollow pith. After that, the pathogen gradually spread to the root, causing the root bark cortex to rot. If you pull out the diseased seedlings by hand, you can only pull out the xylem and leave the root cortex in the soil. The stem rot of Ginkgo biloba cuttings can also occur under the condition of high temperature or low temperature, which can make the cuttings epidermis sleeve on the xylem and all the phloem parenchyma blacken and rot.

2. control methods of root rot and stem rot of ginkgo biloba seedlings

1. Control methods of stem rot of Ginkgo biloba.

The main results are as follows: (1) according to the causes of stem rot of Ginkgo biloba, prevention should be given priority at present.

(2) sowing early to sow as soon as the soil is thawed, this measure is beneficial to the Lignification of seedlings in the early stage and enhance the resistance to high temperature on the soil surface.

(3) reasonable dense sowing is beneficial to give full play to the group effect of seedlings and enhance the resistance to the adverse environment. The experiment showed that the smaller the seedling density, the higher the incidence, and the higher the density, the lower the incidence. Practice has also proved that in the past, after sowing 25~40kg seeds per mu, such as changing the sowing rate of 80~l00kg seeds per mu, not only the incidence decreased, but also the seedling yield per unit increased, which not only saved the land but also reduced the disease.

(4) after the seedlings of underground pests are harmed by underground pests, they are easily infected by stem rot pathogens. Therefore, attention must be paid to the elimination of underground pests before and after sowing.

(5) to prevent mechanical damage of seedlings, annual seeding seedlings or annual transplanting seedlings must be careful not to damage the roots of seedlings in the process of loosening soil, weeding or seedling planting, otherwise it is easy to cause stem rot.

(6) shading and cooling in order to prevent the increase of ground temperature caused by solar radiation, measures such as setting up shade shed, covering grass between rows, planting corn, cutting and shading should be taken to reduce the harm to seedlings.

(7) Irrigation and spraying should be timely in order to reduce the surface temperature in the high temperature season, and spraying should be adopted where there are conditions, which is more beneficial to reduce the occurrence of diseases.

(8) drugs and biological control combined with irrigation can be sprayed with various fungicides such as topazine, carbendazim, Bordeaux solution and so on. Antagonistic actinomycetes can also be added when topdressing organic fertilizer in the middle of June, or plant ash / superphosphate (1GB 0.25) and antagonistic actinomycetes can be added.

2. Control methods of Ginkgo biloba root rot.

Root rot usually occurs in June. The prevention and control methods are as follows:

(1) remove the diseased plant in time and burn it centrally in time.

(2) spray with 1000 times of topiramate.