What Causes Butternut Squash Plants to Yellow?

Updated June 17, 2017

When it comes to harvest time, the benefits of growing your own garden are endless. Unfortunately, even the best tended gardens can experience diseases or pests. Sometimes when butternut squash is growing, the leaves turn yellow for no apparent reason. If the cause behind the yellow leaves is not dealt with early, your crop of butternut squash may be in jeopardy.


One of the simplest problems to deal with when squash leaves turn yellow, according to Gardening Know How, is dehydration. When squash plants do not get enough water, the leaves on the plant will turn yellow. If leaves have turned yellow, the dirt is dry and the plant looks wilted, watering the squash may solve the problem. Keep in mind that squash needs about 2 inches of water a week, more in warmer temperatures.

Bacterial Wilt

Bacterial wilt is a common disease among squash plants that will cause the leaves of the plant to turn yellow. Bacterial wilt is caused by bacteria that clogs the vascular system of the plant, according to the University of Illinois Extension. The bacterium is transmitted to squash plants from cucumber beetles. It is important to control cucumber beetles early in the season using insecticides or they may completely destroy the crop before harvest time.

Inadequate Soil

Poor soil conditions can cause yellow leaves on butternut squash plants. When plants do not have enough nutrients, they are unable to thrive. Yellow leaves may be a sign that a plant is not getting enough nutrients from the soil it is planted in. Purdue University's Department of Horticulture recommends using a complete 6-10-10 fertiliser on butternut squash plants to keep them healthy.

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About the Author

Melissa Nykorchuk has been writing professionally since 2002. She has contributed to various online publications and obtained a Bachelor of Arts in English from the Massachusetts College of Liberal Arts.