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Your zucchini turn yellow and die: What are the causes and what measures can be taken?

Because of its amazing taste and multiple benefits, zucchini has always been a staple in most home gardens. Moreover, this tasty vegetable is widely grown around the world. However, sometimes this plant can suffer from a disease that causes it to rot and turn yellow. Your zucchini turns yellow and dies – you may wonder why? We clarify the causes and the appropriate measures to take!

Zucchinis turn yellow and die – What are the causes?

Your zucchini is turning yellow and dying - you may be wondering why

Generally, zucchini turns yellow and rots due to poor pollination, blossom end rot, and diseases or pests. Blossom end rot is usually caused by a calcium deficiency in the fruit. If the plant’s leaves turn yellow, disease or pests are most likely the cause. Light,and water conditions can also be a reason for yellowing.

Poor pollination – what to do

If there is little rainfall where you live, water your plants once or twice a week

A common problem that can lead to yellowing of the plant’s leaves or fruit is poor pollination. Poor pollination, in turn, leads to weak fruits that may eventually drop before they are ripe. This premature dropping of fruit is called fruit abortion. In areas where the insects that cause zucchini pollination are less abundant, fruit yellowing is more common .

Hand pollinating zucchini is a simple method that requires a steady hand

Tips for hand pollination:
Hand pollinating zucchini is a simple method that requires a gentle touch and a steady hand. There are two ways to accomplish this. You can gently pick the male flower and stick it into the female flower, or you can use a small paintbrush. Most gardeners prefer a small brush because it does not damage the plants. To ensure insect pollination, try growing other plants near zucchini , such as companion plants that can attract more pollinators. Some good companion plants are nasturtium, corn, oregano, rosemary and peas.

Blossom end rot causes plants to turn yellow.

Zucchini turn yellow and die - What are the causes


Blossom end rot is another major cause that can lead to yellowing of your zucchini plants and fruits or premature fruit drop. One of the main causes of this plant disease is a lack of calcium in the soil where you planted the plants. According to the University of North Carolina, blossom end rot is caused by low soil pH or stress to the plants due to unusually harsh weather (cool or hot), drought or even wet soil conditions. Blossom end rot not only causes yellowing of leaves and other plant parts, but can also cause poor growth.

Zucchini turns yellow and dies - what to do to save the fruit

Tips for preventing blossom end rot:
Act before it’s too late; prevention is always better than cure. If your zucchini has already turned yellow, it may already be too late. According to Cornell University, consistent soil moisture is necessary to prevent blossom end rot. Water in dry weather, as most vegetables need between 2.50 and 3.80 inches of water each week through irrigation or rainfall to grow well. If there is not enough rainfall where you live, water your plants once or twice a week.

Blossom end rot is one of the diseases that leads to yellowing of zucchini plants


Water your plants evenly and thoroughly. Give a suitable fertilizer with low nitrogen content before planting the plants. Too much nitrogen will cause an imbalance between roots and leaves. Adding lime to balance the soil pH is another way to prevent blossom end rot in zucchini. As we know, plants thrive at pH levels between 5.8 and 6.8.

Pest infestation – a common cause of yellowing.

Pests are also the reason for many diseases on zucchini

Pests are also the reason for many diseases. These insects cause the transformation of various viruses, which in turn lead to poor nutrition of plant fruits and flowers. Aphids are one of the insects that commonly attack such plants. According to Purdue University, Phytophthora capsici is a fungus that can destroy a cucurbit field.

Tips to prevent pests on your zucchini:

  • Squash bug – hand picking. Compost or bury plant debris after harvest.
  • Squash rootworm – Remove by hand and destroy.
  • Striped cucumber beetles – Apply appropriate netting or tents made of cheesecloth. You can also use floating row covers over young plants. Apply at planting and remove after flowering.

Zucchini turn yellow and die because of diseases

Zucchini needs full sun, which means at least 6 to 8 hours of direct sunlight per day

  • Bacterial wilt – Remove and destroy affected plants.
  • Powdery mildew and scab – Avoid wetting the leaves if possible. Water early in the day to allow the above-ground parts to dry as quickly as possible. To improve air circulation, zucchini plants should not be too close together, and weeds around the plants and in the garden must be removed.
  • Viral disease – Immediately remove and destroy the entire infected plant, the soil around the roots, and the soil attached to the roots. Eliminate wild cucumbers and milkweed in the vicinity.
  • Cucumber Mosaic Virus – A virus that can cause premature fruit drop or death of your plants is cucumber mosaic virus. This virus is caused by a certain type of aphid that normally feeds on the leaves of the plants. It is very important to control aphids early in the season by washing them off with water early in the day.

Avoid lack of sunlight

Zucchini turns yellow and dies because of diseases

During the growing season, any sign of yellowing leaves or fruit could indicate that the zucchini plant is not getting enough sun. Zucchini needs full sun, which means at least 6 to 8 hours of direct sunlight per day (more is even better). If your vegetable patch is too shady, this could be the cause of yellowing leaves or fruit.

Zucchini will turn yellow and die: Over,or under watering.

Overwatering or underwatering can cause the plants to turn yellow

One of the most common reasons for yellowing leaves or fruits on zucchini plants is too much or too little water. If you overwater your plants, the roots will atrophy and not be able to properly support the plant. Pay special attention to how much water you give your zucchini if they are growing in heavy, clay soils. Clay soils are especially prone to overwatering because the densely packed soil particles trap water and excess water cannot drain away. Too little water can also cause yellowing. As roots absorb water, they also absorb nutrients from the soil to feed the plant (and produce chlorophyll).

A common problem that can lead to yellowing of the plant's fruit is poor pollination

If there is no water, there is no plant food, and the leaves and fruits begin to turn yellow. Sandy soil can become the enemy here, as water is easily washed away by the loose soil particles. If you’re growing zucchini in sandy soil, check the soil regularly to make sure it doesn’t dry out. To help your sandy soil hold water better, compost is the solution here as well. Adding compost to sandy soil adds humus and helps bind the sandy soil. Both help retain water and prevent as much water from being lost to runoff.