Click [Follow] in the upper right corner to master more planting techniques and achieve a bumper harvest!
Speaking of citrus dragon disease, it is estimated that it is a major heart disease of citrus growers, as early as the 1970s from Guangdong to Fujian, and then introduced to Guangxi, Hunan, Jiangxi, Yunnan and other places, known as "the number one murderer of citrus" and "citrus cancer". No matter what variety you plant, how many acres you plant, as long as you are targeted by it, there is basically no cure, you can only cut it down and burn it.
So, what are the symptoms of citrus infection with dragon disease? How to prevent yellow dragon disease? Today we will take a look together, hoping to help you avoid this "big devil"!
Its symptoms are very similar to the symptoms of zinc deficiency in fruit trees, but on closer inspection, there are also obvious gaps, mainly these 3 kinds:
1. Mottled type
Mottled yellowing is what we call a golden flower arrangement. In the branches, there is suddenly a branch that looks like a zinc deficiency leaf yellowing, but unlike zinc deficiency, there will be pyllids on the branches, indicating that it has been infected, but the virus has not spread yet.
2. Red nose fruit
Fruiting trees with dragon disease will fall fruit in July and October, and if there is a lot of rain or drought, it will aggravate the disease. Because the root system absorbs nutrients, it is easily hindered by pathogens, resulting in nutrients that cannot keep up with the formation of fruit fallen fruits.
Characteristics of falling fruit: there are yellow and green, and some are red-nosed fruits, and there are no fruit fallen fruit in the surrounding trees, only this one, but it is different from acute anthrax. The fruit stalk that falls from the yellow dragon disease is raw blue and falls fruit from a single tree; the fruit of acute anthrax falls fruit, the stalk is black, or dry, usually in pieces.
So, if your tree fruit fall symptoms are in line with the characteristics of yellow dragon disease, then don't be distressed and cut it down immediately.
3. Uniform yellowing
With yellow dragon disease, the branches are yellow very evenly, the fruit will fade blue and color in advance, the size of the fruit is uneven, the shape of the fruit is long, and the leaf veins are swollen and yellow, and the leaf texture is brittle, which is typical of yellow dragon disease.
So, how to distinguish from the leaves is zinc deficiency yellowing, or yellowing of yellowing?
Zinc-deficient leaves are particularly pointed, with short branches and short internodes, but the internodes of yellow dragon disease are relatively long, and the leaves are larger than zinc-deficient leaves. Moreover, the leaves that lack zinc are rolled down at the beginning, and the leaves of huanglongbing disease are upwards.
1. Prevent and control psyllids and cut off the vector of huanglongbing disease
Why put anti-wood lice first? Because at present, there is no medicine that can treat huanglongbing disease, and the vector of huanglongbing can only be cut off by preventing psyllids.
In the past, there were only 1-2 psyllids on a tree, and now the outbreak is very serious, with more than 100 on a single branch, and if you think about it, you can see how serious the situation of yellow dragon disease is.
The cause of Xanthaloficinalis, mainly Gram-negative bacteria, is transmitted by psyllids, which are lazy and, if not surprised, can multiply in a tree for several generations.
If there are no young shoots, they will migrate. In windless conditions, it will migrate to tens of meters around, and when the wind reaches level 3-4, it can migrate more than one kilometer.
And the wood lice like to stay, empty and high-lying places, mainly concentrated in the east, south and west directions, close to the wind outlet, so you should pay attention when inspecting the orchard.
When 1-2 lice are found in the garden, they can be sprayed around the orchard; if there is a 3-4 wind blowing, they must be sprayed in the whole garden; when the young shoots come out to 1 cm, they can be sprayed every 10 days.
Because psyllids are highly transmissible, as long as they stay on the branches for 5 hours, suck the sap, and then run to another tree for 5 hours, then the tree will be infected.
Repeatedly, the infected area of the entire orchard will become larger, like a ring slowly spreading. So if you find a wood lice, don't be soft and kill it immediately.
2. Buy healthy seedlings
What is a Healthy Seedling? I must go to the nursery, personally check whether there is an insect net, which is the most basic, because the risk of infection of yellow dragon disease is very high, but the symptoms are not typical, and even when you buy, the leaves are still lush and green, no different from healthy seedlings, and the insect net can at least reduce the risk.
In addition, because the symptoms are not typical, when buying seedlings or scion, samples can be sent to a special institution for PCR testing.
Generally like open-air seedlings, it is not recommended to buy, the risk of contracting huanglongbing disease is very large, it is recommended to go to the Chinese Academy of Sciences or qualified institutions to buy.