Plant canker is a dangerous disease

Plant canker is a dangerous disease
Plant canker is a dangerous disease

Plant canker is a dangerous plant disease. It is caused by the imperfect fungi Kabatiella, Colletotrichum, and Gloeosporium. These fungi can cause considerable damage to crops such as watermelon, pumpkin, beans, grapes, zucchini, melons, cucumbers, and even citrus fruits.

In addition, Plant canker affects walnuts, almonds, native and berry shrubs very close to us, currants, raspberries, and gooseberries. This problem is a big subject, which many scientists are studying, but we will try to tell you as briefly and interestingly as possible how Plant canker occurs on crops, how to control it, or, perhaps, only to prevent it. Thus, Plant canker.


Various diseases in humans, as well as plant organisms, are usually affected when immunity is weakened, i.e. there is no protection. In this case, the disease can enter weak plants through wounds or cracks in the surface, and can also spread through the seeds of already infected plants or parts of dead plants. plant canker spores are easily spread by wind over considerable distances and can be carried by insects, water, i.e. raindrops or dew, or irrigation water. The disease is most actively developed and occurs most often just when air or soil moisture is high.


The disease usually begins on a single leaf: it starts as a brownish-red spot with brownish-red margins, usually darker in color, and maybe a bit yellow or dark. Over time, these generally inconspicuous spots become larger and larger, to the point where they literally join together.

In addition, symptoms of Plant canker are sometimes observed on both branches and shoots. These are usually literally depressed areas through which there is either a significant delay or no nutrient passage at all. In most cases, these areas have the appearance of oblong light brown spots that grow larger, darker, and darker over time, forming a brown or dark purple rim around these depressed spots in the final stages.

If the weather is dry and fairly warm at this time, all Plant canker-affected areas usually have visible cracks, but if it rains and the air is completely saturated with moisture, the affected stems and buds begin to actively damage and they literally rot, breaking off at the slightest touch or gust of wind.

If this disease is ignored, the leaves will turn brown and wilt, and then practically the entire above-ground part of the plant will die. As we have already mentioned, Plant canker develops most actively in high humidity or excessively wet conditions. The following is the ideal combination for Plant canker: temperatures of 73°F (23°C), moisture of about 87-88%, low levels of potassium and phosphorus in the soil, and high acidity – under these conditions, the plant is destined to get Plant canker. let’s treat blue ear disease.


So, it’s not all bad, and fortunately, much of it is treatable. We know that Plant canker is fungal in nature, so you can fight it with antifungal medications (fungicides). Medications change from year to year and some are banned, but we will give examples of the most effective against Plant canker are the Cuproxat USA (fairly safe, copper-based, but not helpful), and some fungicides that are composed of copper chloride.

Do not expect these drugs to be a panacea, eliminating Plant canker with just one treatment, it would be nice if they would help: you usually need two or three treatments, one week apart. By the way, it is very acceptable to change the preparation, not to treat the same person, and to pay attention to the precipitation outside the window. Therefore, if it rains after the treatment, all the work will obviously be in vain.

To suppress the spread of infection, microbial agents that are more friendly to the environment are used.

Important: Please check the list of approved varieties, as these things change very quickly. Always read the instructions on the package regarding the hazard class of the preparation. Even if the preparation is classified as hazardous (Class III), i.e. not considered that dangerous, you must wear a respirator and gloves. Given that Plant canker can also affect indoor plants, take them to ventilated decks and balconies after handling. Remember that chemistry is no joke and the packaging often specifies in detail how to apply the drug, i.e. dosage, timing, pre-harvest period, etc. This is very important.


Prevention is the best cure (golden words). You must keep in mind that the source of infection can already be on the seeds in your hands, on any garden tool that almost no one also, not disinfected but not cleaned, as well as in the irrigation water (for example in a good old black lacquered bucket in the garden), and on the wings or other body parts of insects.

Once the humidity increases and the above conditions occur, the microorganisms are immediately activated and the disease itself begins to progress. In order to build a defense against Plant canker, you must always follow a crop rotation, always disinfect the seeds before sowing, even if they are collected by your own hands, remove them from the garden and vegetable residues, preferably digging the soil in this way so as not to destroy large patches of soil, then the infection hidden in the soil has all the chances to freeze.

Gardening tools, if you do not care about infections, at least consider keeping them safe because they are expensive (although expensive): just wash them, dry them, wrap them in greaseproof paper, and put them in a dry and clean place.

When mating and budding, take with you 10-15 grams of common alcohol in each cut of the eye or cut in the tree, wipe the blade and soak it in alcohol. In this way, you will not spread the infection.

Isolation treatment with fairly safe preparations is also quite acceptable. For example, in early spring, when the plants are still sleeping, you can treat them with Topsin-M, into which you pour (1-2 ml) growth promoter or immunomodulator and plant growth biomodulator, and the infection may not appear at all.


Now that we have talked about Plant canker in general, let’s talk about the signs of its manifestation in the main crops, including flower crops, as well as the names were approximately chosen to combat this disease.

Cucumber Plant canker

From it, you can see the leaves, stems, fruits of the plant and already in the seedling stage. Notice that the manifestation of Plant canker can be on the seedlings of cucumber, in the area of the neck of his roots, there will be visible sunken spots that turn into ulcers, while the seedlings just lie down. In adult plants, yellow or brown spots appear on the edges of the leaves, at first only a few millimeters in size, and then rapidly increase dozens of times.

Eventually, through-holes will form where the spots are, and the fungus, having lost interest in the leaves, will move to the stem and finish its black work with the fruit, on which brown spots will form up to a few millimeters deep. If a Plant canker is found in the root zone, you will need to pour 10-15 grams of 1% Bordeaux mixture under the plant, but the soil must be watered thoroughly beforehand. One treatment is usually not enough, you need to spend them two or three times. On the leaves, pour in copper oxychloride.

Tomato Plant canker

Usually, adult tomatoes suffer from Plant canker: first, the upper leaves wilt, seemingly due to lack of moisture, and then spots with black sclerotia form on them. On the fruit, black and sunken areas of about 0.4inch (1cm) are usually clearly visible, darkening and softening over time. Professionals recommend the use of preparations such as Kumulus DF to control Plant canker, as well as the use of colloidal sulfur, Bordeaux mixture, or copper chloride.

Potato Plant canker

Plant canker can affect both tubers and stems. The stems usually have light brown spots, while the tubers have faint dark brown spots. If you miss a tuber and put it into storage, it can ruin the whole batch as it will develop and spread further into wet rot. Potato Plant canker is difficult to control, it is easier to plant it in the same place every four years, treat the tubers with a fungicide before planting, remove weeds, especially “classmates”, and remove all plant residues from the plot after harvest. After that, dig the soil deeply and do not loosen it for the winter.

Zucchini Plant canker

This disease of zucchini affects the entire above-ground part of the plant and the plant dies. If you find yellow-brown spots on the leaf plates, treat the plants with a colloidal sulfur solution. On zucchini, which I tested myself and was convinced of its effectiveness, you need to use 50 grams of colloidal sulfur per bucket of water and treat all parts of the plant affected by Plant canker with this solution. A neighbor treated with Bordeaux mixture sprayed 1% to the plants and then the disease disappeared, said it was also effective.

Watermelon and melon Plant canker

Usually, the stems of watermelon and melon are most affected by Plant canker and they become extremely fragile. Affected fruits do not grow and do not accumulate sugar. On diseased fruits, sunken spots of decay can be clearly seen. As soon as signs of Plant canker are detected, it is necessary to treat plants three times with (copper (Cu2+) fungicide in liquid form), strictly according to the dosage on the package.

The first time – when the stems start to grow, the second time – when the wilt starts to form, and the third time – two weeks after the second treatment. But here it is important not to delay the treatment: from the last treatment of the season to the collection of fruits should be 25 days, no less.

Treatment of plant canker on shrubs and trees
Treatment of plant canker on shrubs and trees


Currant Plant canker

First, Plant canker appears on the lowest leaves with clearly visible brown spots that increase in size very quickly. Next, the leaves dry out and fall off, and the disease moves to the shoots, forming depressed spots on them, which become wounds. Eventually, white ulcers also appear on the berries. It is usually impossible to save the harvest, but it is useful to treat the shrubs with a sprayed fruit crop fungicide solution in the fall, then replant the soil and repeat these treatments early in the spring.

The following season, once the whole crop has been harvested, the bushes can be treated with 1-2% Bordeaux mixture, or with a fungicide if the plants are affected again, such as Kumulus DF.

Gooseberry Plant canker

In fact, all actions are the same as for gooseberries, except that attention is paid to the time of ripening so that the drug does not get on the berries ready for picking.

Raspberry Plant canker

On raspberries, Plant canker starts with gray-blue dots on the leaves and ulcers on the shoots. Very well helped by modern fungicides, can help 1% Bordeaux mixture or copper chloride solution at a rate of 40 grams per bucket of water (standard per square meter of raspberry).

Grape Plant canker

Grape Plant canker rarely attacks grapes, but as they say, quite properly. It develops on all above-ground organs of the plant, but only young tissues not older than one month are affected. At first, gray spots with reddish or dark borders appear on the leaflets, these spots grow and increase in two stages, after which the leaf tissue simply falls off and a through-hole is formed.

The shoots develop brown spots and the inflorescences develop ulcers that cause them to die. Those who treated the grapes wrote that treatment with the usual 1% Bordeaux mixture could cure it, but treatment with Plant canker could not be delayed. Next year, without waiting for a second outbreak, the plants must be treated again with 1% Bordeaux mixture when their shoots reach 4inch (10cm) in length.

Of course, serious winegrowers also use more serious preparations, some of which also have a common copper sulfate component: obviously, everything depends on the growing area.

Strawberry Plant canker

On garden strawberries, Plant canker can “cut” 85% of the entire crop, that is, invalidate all ideas. The most interesting thing is that it is often invisible and only when the plant is ready to die, signs of infection appear: small sunken spots of alkali brown color form on the tendrils and on the upper part of the leaves, they merge into ulcers and the leaves die. To prevent Plant canker, it is necessary to use fungicides and three to four treatments should be applied during the flowering period. Products such as the new Signum fungicide formulation from the UK can help; it is a good European treatment and has been tried in my area.

Cherry Plant canker

Plant canker on cherries appears suddenly in mid-summer, with dry and rather hard spots on the berries to the touch, which can expand to cover the entire surface of the fruit. It helps to prevent the appearance of Plant canker on cherries by annual hygienic pruning and by treating the plants with 1% Bordeaux mixture in spring, when the buds are still awake. Previously, in my garden to help with my lime milk, I took about 10lb of lime, dissolved it in a bucket of water, and then treated all the plants with this solution.

They say that if you circle 150-200g of wood ash per year on the roots of cherry trees, then a Plant canker will not appear.

Immediately after removing all to the last berry, treat the plants with a copper sulfate solution, which should be 100 grams of copper sulfate diluted in a bucket of water per tree. After the leaves have fallen off, be sure to remove them all and treat the plants with 200 grams of urea dissolved in a bucket of water.


Plant canker of Laceleaf

At first, small brown spots appear on the edges of the leaves, then they grow and eventually fuse with each other and the leaves die. For sick plants, it is best to remove all diseased organs and transplant them into fresh soil and treat them with any approved fungicide on an open and ventilated terrace.

Plant canker of orchids

The spots on the leaves look like stigmas and the edges look like they are burnt. Loose growth can be seen at the base of the leaves. Try to trim off all affected parts and cover the living tissue with crushed charcoal. The substrate needs to be replaced. Treat the orchids with fitosporin m-fungicide on a ventilated terrace.

Plant canker for cacti

Cacti only get Plant canker if they are severely waterlogged. Cacti are very difficult to cure. Usually, sunken spots with bright borders (a sign of Plant canker) simply need to be cut off with a sharp knife, grabbing the healthy tissue and treating it with finely crushed charcoal. Then you need to stop watering for at least a month and the fungus should die and the cactus should survive.

So, we’ve told you about Plant canker, if you missed anything, don’t judge, ask questions in the comments and we’ll answer them.

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