The easy-care zucchini plants are a popular garden vegetable. The tropical plants with the scientific name “Cucurbita pepo subsp. pepo convar. giromontiina” belong to the descendants of the oldest cultivated plants in the world. Various zucchini diseases can stunt growth and destroy crops.

Various zucchini diseases

When growing the plants, various diseases can throw a spanner in the works. A common subdivision is made into fungal and viral diseases. Below are common diseases of the pumpkin plant.

Common fungal diseases of the cucurbits

Various diseases of the zucchini plant come from fungi. Below you will find an overview of common diseases to protect your plants effectively.

focal spot disease

A so-called sac fungus causes focal spot disease. In wet weather and regular rainfall, the spores are distributed. The disease spreads and survives the cold season. At high temperatures, the fungus develops faster. The vegetable plant gets large spots that are unevenly distributed throughout the plant. With a crop rotation every 3 years, you can protect the pumpkin plants and minimize the risk of disease.

Wrong mildew

Downy mildew is another fungal disease. In warmer countries, this disease destroys the zucchini crop. The spores of the fungi cling to the plants and eject their germs. These get into the cucurbits. Yellow and brown spots appear on the surfaces of the leaves. A mushroom network develops on the lower side. The leaves will gradually wither and the plant will be completely infested if you do not take countermeasures quickly.

Note: In the case of downy mildew, acute measures are required. You can use fungicides to control the disease and protect your zucchini.

powdery mildew

Powdery mildew is a common sac fungus that spreads quickly with the help of spores. In the course of the disease, whitish fungal spores develop on the leaves and stems, which are not clearly defined. The mycelia of fungus will spread all over the leaf over time until the leaves of the zucchini plant die off.

Tip: Choose resistant varieties to reduce the risk of disease. Resistant zucchini plants are less susceptible to powdery mildew. If the plants are infested, a fungicide is the remedy of choice. As a natural option, regular watering is suitable, since an excessive supply of water destroys the spores of the fungi.


The gray mold is a so-called weakness parasite that exploits the situation of weakened plants. Younger squash plants are susceptible. The following conditions are considered ideal for the fungus to spread on the plant:

  • little light
  • high temperatures
  • high humidity

The disease is first transmitted by splashing water. A fungal network forms on the plant. Pale and glassy areas on the leaves and flowers are the result. As the disease progresses, mold will cover the zucchini. The leaves and shoots wither and die.

Tip: Regular cleaning of garden tools is necessary to prevent gray mold. When infested, fungicides help fight the fungal spores.

seedling diseases

Common zucchini diseases are the so-called seedling diseases. Different fungi and bacteria meet. The disease regularly spreads from soil fungi to the crop. High temperature and humidity as well as lack of ventilation increase the risk of the disease. The seedlings weaken and die.

Note: Combating seedling diseases is not possible in private gardens. Avoid the disease through good hygiene and steaming the floor.

gumstick disease

The so-called gum stem disease (Ascochyta cucumis) is one of the diseases that develop in bad weather. Rain and wind carry the spores onto the plants. The parasites get inside the zucchini and accelerate wilting. The plants first show brown-grey spots and then traces of yellow before dying. Low humidity can help prevent gumstem disease. After disease, removal of all infected leaves is required. Fungicides help control it.


Fusarium wilt is another fungal disease that affects plants via spores. Wounds are the entry points for the pathogens. The young plants wilt and the leaves dry out more and more.

Bacterial and viral diseases of zucchini

Fungal diseases dominate in the home garden. Nonetheless, there are zucchini diseases that are caused by a virus or bacterium.

yellow spotting

Pumpkin yellow spotting is a viral disease. The so-called Cucumber Mosaic Virus is long-lasting. After two weeks of infection time, the leaves change by yellow spots appearing. The individual leaves are then deformed and the entire plant is compressed.

Note: Weeds act as hosts for cucumber mosaic virus. Regular weeding is necessary to prevent disease.


Zucchini diseases include zucchini yellow mosaic potyvirus disease. Seeds and aphids pose a threat to the crop. The plant wilts and the number of fruits decreases. Yellowish spots are typical of the disease. With a resistant seed you increase the resistance of your plants. Hygienic cleaning of garden tools minimizes the risk.

Angular leaf spot disease

If angular and oily spots spread across the plant, it is angular leaf spot disease. The bacterial disease loves a hot and humid climate. The leaves turn brown and die. With generous spacing between plants and good ventilation, you reduce the risk of disease.

Tips for safe cultivation

There are several tips to make the zucchini resistant and protect them from diseases:

  • choose hardy varieties
  • plant in a warm and sunny spot
  • moderate watering and fertilizing
  • Protection in frost and cold weather
  • prevent cold, wet weather conditions

frequently asked Questions

When the cucurbits don’t feel comfortable in their environment, diseases develop. Incorrect temperatures and neglected care can promote the development of zucchini diseases. The same applies to irregular cleaning of garden tools.

A moderate fertilization of the plants is ideal for a balanced diet. Organic fertilizers add value to the zucchini. If you fertilize unilaterally, the tissue of the plants changes negatively. Zucchini diseases have an easy time.

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