Have you found white or yellow spots on your zucchini leaves and don't know what to do? Our article will help you recognize the “offender” and cope with dangerous diseases of your favorite vegetables.
Diseases and pests of zucchini can destroy the crop in a fairly short period of time. Therefore, it is important to know the enemy by sight and, armed with modern means of combat, not to offend your garden crops. What is the most common problem with zucchini and its popular variety, zucchini, when grown in open ground?
Apical bacteriosis of zucchini
If you are wondering why your zucchini has turned yellow, the first thing to look at is the weather and growing conditions for these vegetables. If there is damp soil in the beds, and the air does not circulate well between the plants, then there is a high probability that the zucchini has contracted apex bacteriosis. With severe damage, the ovaries not only turn yellow, but also rot.
The fruits stop developing and become glassy. Some time later, brown spots form on the deformed zucchini.
Measures to combat zucchini bacteriosis
Diseased plants cannot be saved. Therefore, the fight against fruit bacteriosis consists mainly of competent prevention.
Sow healthy seeds. 2-3 months before sowing, treat them with any systemic fungicide (according to the instructions). Care for your plants properly. Water the zucchini with water at room temperature and do not allow the soil to become waterlogged.
Trimming green leaves
Dry areas of the plant can be torn off; this will not harm the bush. If it comes to green leaves that shade the “neighbors” and the main stem, then careful pruning should be done. To do this, it is advisable to use a sharp knife to cause less damage to the stem.
Try to prune close to the base of the main stem. If you leave small petioles, bacteria can accumulate on them, which will lead to rotting and death of the entire plant.
Powdery mildew on zucchini
The main symptom of the disease is a white coating on the leaves of zucchini. This is a fungus that deprives the plant of nutrients and thereby leads to death (the leaves curl and dry out).
Sometimes white spots appear on the stems. Fungal spores are carried by water and wind and can infect other garden and vegetable crops, so don’t hesitate.
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Measures to combat powdery mildew on zucchini
Follow the watering schedule, avoid overwatering and strictly adhere to the norms for applying nitrogen fertilizers, since when there is an excess of them, the fungus develops rapidly. Remove the affected parts of the plant, and spray the remaining zucchini with a fungicide (Baktofit, Alirin, Fitosporin-M).
When choosing seeds, give preference to varieties that are resistant to powdery mildew.
Bush formation
Zucchini leaves are wide. The plate is carved. There are 5 extremities on it, which are separated by intervals. The leaf color can be plain, green, or with silver stripes that form a specific pattern.
The light pattern protects the bush from ultraviolet radiation, so the crop can tolerate extreme heat, more than 35 C.
A zucchini bush can be compact or spreading. Plants can prevent neighboring crops from developing properly, so when planting it is recommended to maintain planting density.
The planting pattern is indicated by the manufacturer. Experts recommend forming a bush and removing some leaves. This solves the following problems:
- soil ventilation improves; a dense bush can cause waterlogging of the soil; this causes disruption of the plant’s metabolic processes and the development of fungus on the soil surface; the fungus quickly spreads to the stems, affecting the inflorescences and ovary;
- in dense vegetation, pollinating insects cannot reach the flowers; removing excess shoots will allow pollinators access to the inflorescences;
- the sun cannot fully influence the fruit if it is under a lush plant crown; being in the shade, zucchini ripen poorly and may become sick;
- excess shoots take up a large amount of nutrients, which interferes with the normal development of the fetus.
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Formation is carried out 3 times per season. Before the flowering period, before the ovary begins, preventive removal of affected leaves. You can remove 2-3 stems at a time.
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They are cut off with pruning shears and the shoot is grabbed at the very base. If the stem is simply broken, the remaining part may rot, which will lead to disease of the entire bush.
Downy mildew (peronospora) on zucchini
This disease also most often occurs when air humidity is high and plants are watered with cold water. Oily greenish-yellow spots appear on the leaf blade, which over time acquire a grayish-brown tint. They are often powdered with a dirty white coating. The zucchini leaves appear scorched and gradually dry out.
Measures to combat downy mildew on zucchini
At the first sign of disease, stop watering. Spray the plants with a solution of Abiga-Peak, Consento or Trichoderma Veride. If it’s cold outside, cover the zucchini with non-woven material (spunbond, lutrasil, agril, etc.). Ideally, the air temperature should not fall below 22°C during the day and 18°C at night. In addition, when growing zucchini, it is important to observe crop rotation.
What kind of leaves does a pumpkin have?
The leaves are five-lobed and pointed. The seeds of the hard-barked pumpkin are yellow-white, medium in size, with a clearly defined rim. They eat young ovaries, which they begin to harvest in the summer. Hence their name - summer squash.
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Anthracnose of zucchini
If, during the growing season or during harvesting, brown-yellow round spots with blurred outlines form on the leaves, then, most likely, anthracnose has attacked the zucchini. The foci of infection expand quite quickly and soon occupy almost the entire leaf, the spots gradually turn brown. Elongated depressed spots with a yellow-brown coating also appear on the stems. The fruits wrinkle, lose their elasticity, rot and become bitter.
Measures to combat anthracnose in zucchini
The disease progresses with frequent watering during the hottest part of the day. Water the zucchini in the evening, do not allow the air to become waterlogged. In the first stages of the disease, spraying with Abiga-Pik, Consento, Trichoderma Veride, Fitosporin, Agrolekar will help cure zucchini. Most often, anthracnose develops in greenhouses; in open ground, vegetables get sick mainly when the rules of agricultural technology are not followed.
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How to trim correctly and when to carry out the procedure
It is recommended to cut the leaves of the zucchini in several stages. This will significantly increase productivity and ensure proper development and growth of the bushes.
Trimming green mass in stages:
- The first removal of excess foliage is carried out when the first buds are set. Remove everything that creates a shadow.
- The second time pruning is done when dry leaves appear. Damaged and yellow ones must be torn off. They must be removed carefully, without tugging at the bush. The procedure will provide additional illumination to the ovaries, improve ventilation and evaporation of excess moisture, and also prevent infection of the crop with fungal diseases. Removal of dried foliage can be carried out until the entire crop has been harvested.
- It is important to carry out the procedure a third time during the formation of the ovary. Cut off the lower leaves, as well as any damaged ones. This moment is the most important for the development of squash bushes. You need to remove not only yellow and large elements, but also broken elements. To do this, you will have to carefully examine each bush so as not to miss anything. This stage of pruning takes the most time.
Expert opinion
Stanislav Pavlovich
Gardener with 17 years of experience and our expert
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Important! Do not tear off the interfering or yellow leaf. This can damage the entire bush. For work, use a sharp knife or pruning shears. You need to cut as close to the stem as possible, otherwise the petioles will begin to rot.
It is important to prune the green mass when the squash crop is affected by a fungal or bacterial disease. In such cases, entire stems and sometimes bushes are often removed.
Zucchini rot
Zucchini rots for various reasons. For example, dry blossom end rot occurs as a result of a lack of calcium in the soil. The symptoms of this disease are very similar to apical bacteriosis. Root rot spreads mainly in plants in protected soil due to frequent fertilizing with organic matter and high air humidity.
White and gray rot develop due to waterlogging of the soil, thickened plantings, differences in day and night temperatures, lack of microelements or excess nitrogen. White and gray spots with black dots may appear on fruits, leaves, and ovaries.
Measures to combat rot
If there is a calcium deficiency, add ground eggshells and wood ash to the soil (at the rate of 1 cup of ash per 1 sq.m.). Remove all infected ovaries and leaves. Apply foliar feeding to the leaves with phosphorus fertilizer (for example, ash infusion). Spray the soil with Fitolavin solution, and then add unused compost there to restore the soil microflora.
To prepare foliar feeding that is useful for zucchini, fill the bucket 1/3 with ash, fill it with hot water to the very brim and let it sit for two days. After which the infusion is filtered and used for spraying on the leaves.
Prevention measures
It is best to prevent the greens from becoming yellow or dry. Preventative measures will help prevent this phenomenon.
Nutritious soil and fertilizers have different effects on the growth of vegetable crops. It is necessary to select mineral fertilizers wisely. It is best to immediately purchase a complex preparation that is well suited for both seedlings and adult bushes.
Feeding the shoots should be done at least once a week. At the stage of active growth and formation of the root system, it is best to use nitrogen and potassium preparations.
Fusarium zucchini
Fusarium wilt first attacks the root system. After this, the disease spreads to the stem and leaves. They turn yellow, dry out and wither. On a cross section of the shoot, browning of the vessels is noticeable.
Measures to combat fusarium
Dust the bottom of the shoots and roots with wood ash. In case of severe infection, treat with Fitosporin or Sporobacterin according to the instructions. Take measures to improve the health of the soil: sow green manure, water the soil with a solution of an EM preparation (for example, Baikal EM1). Please note: pathogenic fungi die in neutral, calcium-rich soil.
Care after cutting off foliage
To prevent penetration of pathogenic microorganisms into open sections, the bushes after the procedure are sprayed with a weak solution of potassium permanganate or brilliant green diluted with alcohol. After removing excess greenery, zucchini will need watering and fertilizing. In the evening, after moistening the soil, you can add organic matter.
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To prevent weeds from shading the bushes and taking away nutrients, it is necessary to loosen the soil from time to time, going 7-10 cm deeper. Carry out the procedure carefully so as not to damage the roots and stems.
