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It is difficult to find a less capricious and demanding vegetable crop than zucchini. Many gardeners say that they simply forget about them after planting, water them once a week, and then remember only to collect the fruits. But sometimes even zucchini can disturb their owners. They may turn yellow, dry out or even rot leaves, ovaries and fruits. Why do zucchini rot? Why is this happening, and what can be done to avoid such problems in order to get a good harvest without much hassle?
Causes of yellowing and methods of struggle
Vegetable growers often say that for some reason the leaves of zucchini turn yellow, sometimes they even rot, they worry that this is what leads to the fall of the ovaries and, even more unpleasantly, to the decay of the fruit. This does not always indicate illness, but it is certainly necessary to respond. In every plant, even an annual, whose growing season lasts only a few months, the first leaves have time to grow old. So the first leaves of zucchini grow large, and then the time comes when they just lie on the bed, touching the ground. They turn a little yellow and dry out with age, and touching damp earth certainly does not make them stronger.
From the beginning of growth, the plant consumes a lot of nitrogen, which is needed to build up green mass, with enough of it, with proper abundant watering, large strong leaves grow. But over time, when flowering occurs, and then the formation of fruits, the forces of the plant are redistributed, more nutrition goes to its new parts than to the old ones. So the old leaves begin to turn yellow. They need to be removed – carefully cut with a sharp knife at the very stem. This will unload and thin out the bush, there must be air movement inside it, the ground under it also needs fresh air and sunlight, otherwise excess moisture will not evaporate.
If such leaves are not removed, they lie on the ground, there are pathogens and fungal spores in the soil, which will certainly use such a “bridge” between the earth and the plant to begin to act. This should not be allowed. Old leaves should be cut in the morning of a sunny day as close to the stem as possible so that the sun dries the cut and it does not become a source of infection. Some owners treat sections with disinfectants, you can simply make a weak solution of potassium permanganate or brilliant green.
Sometimes the yellowing of the leaves indicates a lack of nutrients in the soil, then the plants should be urgently fed. During the period of intensive growth before flowering, the plant needs a lot of nitrogen, and later it needs more potassium, phosphorus, calcium. A highly diluted infusion of mullein or chicken manure, complex mineral fertilizers, urea and ash are perfect. If the plant simply does not have enough moisture, you need to reconsider the irrigation regime.
Unlike cucumbers, which need to be watered little and often, zucchini needs a lot of water, but rarely. Once a week is enough for them, but so that the earth gets wet 30-40 cm deep. Water the zucchini with warm water so that they do not fall on the leaves. It is best to organize a shallow near-trunk circle around the plant and pour water into it, and then cover it with loose earth, compost or humus.
If depressed spots appear on the leaves, if they do not lighten from green to yellow and further to dryness, but become dark or covered with a thin coating, there is reason to worry. Similar signs may indicate fungal or bacterial diseases. It can be powdery mildew, spider mite, bacteriosis. In this case, you need to remove (cut off) all the affected parts – leaves, flowers, ovaries, and treat the remaining plant with special preparations. You can use “Topaz”, “Ridomil” or others.
If the owners prefer to do without chemicals, you can prepare infusions of garlic, onion peel, celandine, stepchildren of tomatoes or potato tops. Lactic acid helps well against fungal diseases, so plants can be sprayed with diluted whey.
Video “What to do if zucchini start to turn yellow?”
Demonstrative video with examples of what diseased fruits look like, as well as tips on how to fix the problem.
Causes of decay and methods of struggle
If the ovaries and small fruits of zucchini rot, this may indicate an excess of moisture or the plants suffer from a decrease in temperature. When growing zucchini in open ground, the weather can arrange unpleasant moments in the form of a cold rain that has charged for several days. This is very bad, but you can try to install a canopy over the zucchini or just arrange umbrellas. Then, when the rain stops, it will be necessary to loosen the ground so that it dries out quickly, remove the lower leaves that prevent the sun from penetrating to the soil. In a greenhouse, of course, it is easier to arrange for zucchini the desired mode of heat and humidity, in which it is comfortable for them to grow and bear fruit. Under the fruits that lie on the ground, you should put a dry solid material that will prevent the tender young squash from touching the wet ground, it can be tree bark, cutting boards, plastic, non-woven fabric.
The ovaries and fruits can suffer from pests or diseases, then their decay is already a consequence of infection with bacteria, viruses or fungi. Larvae of some insects, fungal spores, bacteria that affect related crops accumulate in the soil. Excessive humidity, temperature changes, watering with cold water can become a trigger for the onset of diseases. That is why it is so important to follow the rules of crop rotation and the basic requirements for caring for zucchini.
You can not plant zucchini for at least a few years in the garden where pumpkins, cucumbers or squash used to grow. Good predecessors for them are tomatoes, onions, garlic, cereals. Lack of iodine or boron in the soil can also cause rotting of the ovaries. If in your area there is a lack of iodine in people, then plants also lack it. At least once a season, you can sprinkle a solution (0,002%) of iodine on the soil. Boric acid is diluted in a proportion of 2 g per 10 liters of water and plants are sprayed with it.
If young squash begin to rot from the stalk, bacterial rot may be the cause. If, in addition to rot on the fruits, a white powdery coating is found on the leaves, then the plant is affected by fungal diseases. In any case, as soon as such signs are noticed, it is necessary to immediately remove all the affected parts of the plant (it is better to destroy, and not just remove), reduce watering, thin out the bush, and treat the entire plant with an appropriate agent. In all these cases, copper chloride treatment will help well.
It is necessary to prepare a solution of 1 tablespoon of 50% copper oxychloride (or take the same amount of polycarbacin) in 10 liters of water. You can use special preparations “Barrier”, “Barrier”, just carefully study the instructions, pay attention to the timing of use and the timing of fruit ripening. Traditional methods of dealing with diseases also work well. A decoction of ash, garlic, chamomile is mixed with laundry soap and plants are treated with this preparation, paying attention to the underside of the leaves. It must be said that harmful microorganisms in greater or lesser quantities are always present in the soil, but plants do not always suffer from them. So that zucchini do not get sick, in order to get a good harvest without hassle, you need to monitor the temperature and amount of water, watering regularity, prevent plantings from being thickened, thin out the bushes in time so that all parts of the plant are available to fresh air and sunlight.
Video “Secrets to help grow healthy and prolific zucchini”
Informative video with useful tips for growing zucchini.