Pumpkin leaves turning yellow

Troubleshooting Pumpkin Plant Wilt: How To Fix Wilting Pumpkin Plants

Alas, your glorious strong, healthy pumpkin plants are wilting and yellowing. There’s nothing as sad as having seemingly healthy plants one day and then almost overnight, witness drooping, discolored foliage. Before you can figure out a fix to the problem, it’s probably a good idea to get an idea of why pumpkin plants wilt.

Help! My Pumpkin Plants are Wilting!

There are several reasons for pumpkin plant wilt. The best way to figure out which one may be the cause of your wilting pumpkin plants is to rule out the simplest explanation first.

Lack of water might be the reason for pumpkin leaves that are wilting. Although the large leaves aid in shading the soil and keeping roots cool, the plants still need water. During the heat of the summer, pumpkins need between 1-1 ½ inches (2.5-4 cm.) of water per week. Water the pumpkins deeply and slowly once a week at the base of the plant rather than overhead briefly each day.

During extended heat waves, you may even need to water a bit more. It’s not unusual to see wilting pumpkin plants during the heat of the day, but this should be temporary. If you see that your pumpkins are wilting in the morning, they’re most likely water-stressed.

Diseases causing wilting pumpkin plants

Other reasons for pumpkin leaves wilting and yellowing are less benign than a simple lack of irrigation. In these cases, wilting is caused by disease and can get so severe that the plant will die.

  • Bacterial wilt – Bacterial wilt is caused by Erwinia tracheiphila, a bacterium that is spread via the cucumber beetle. It invades the vascular system of the pumpkin, blocking water uptake. Usually, it begins with one leaf and then spreads to the entire plant. If you suspect bacterial wilt, cut a stem at ground level. Hold the cut end to your finger. If sticky goo comes away when you remove your finger, you have bacterial wilt. Since this disease is caused by beetles, insect control is the best bet to thwart the disease before it assaults the entire pumpkin patch.
  • Fusarium fungus – Fusarium crown rot is a fungal disease that lives in the soil and is spread through movement of wind, of you, of mechanical equipment, from critters, etc. The initial symptoms are yellowing of the foliage, followed by wilting and necrosis. The disease can overwinter in the soil and has no chemical control. The only thing to be done to combat crown rot is a lengthy crop rotation.
  • Phytophthora blight – Phytophthora blight is another fungal disease that is an equal opportunity infection, attacking many types of veggies, not just pumpkins. Again, it overwinters nicely and lives indefinitely in the soil. It thrives in wet, cool fall weather. Primary symptoms are collapsing vines and pumpkins covered in a cottony mold. Again, the disease is spread through movement. Practice crop rotation and provide well-draining soil to fight this blight and use fungicides as directed. Pythium is also a fungal disease with similar symptoms and controls.

Pumpkin leaves wilting due to insects

While diseases are a factor as to why a pumpkin has wilting leaves, insects are also often responsible.

  • Vine borers – Squash vine borer larvae love to feed on pumpkins at the base of a stem, resulting in yellowing and wilting of leaves. The resulting holes are often seen to be filled with the larvae green to orange poop. Once the larvae are munching away on the pumpkins, there is little you can do. Pull up any plants killed by the borers and if timing permits in your region, plant a second batch. The best way to quash the insects is to look for the adults buzzing around at the end of June, before they lay their eggs. Set yellow trap pans filled with water. The adults are attracted to yellow and will fly to the trap and get trapped in the water.
  • Squash bugs – Squash bugs are another insect fond of snacking on your pumpkins. Again, their feeding causes yellowing and wilting foliage. The large, flattish adults overwinter in cozy niches and emerge in the spring to feed and lay eggs on squash foliage. They suck the sap out of foliage disrupting the flow of nutrients and water to the plant. Both eggs, nymphs, and adults may be present at any one time. Remove or knock off any nymphs and adults and drop them into soapy water. Look under leaves. Insecticides may also be used to manage squash bugs, especially if the plants are wilting early in the growing season.

Overall, pumpkins can be afflicted with a number of things that can cause wilting and yellowing. The best defense is to begin with healthy plants in well-draining soil amended with nutritious compost. Water consistently and practice proper fertilization.

Keep a close eye on the plants to inspect for insects before they become a problem. Keep the area around the plants weed and plant detritus free. A healthy start will enable the plants to fight off or withstand any potential disease or insect attacks and give you time to facilitate a control plan.

Things That Can Make Your Pumpkin Leaves Turn Yellow & Brown

Hemera Technologies/Photos.com/Getty Images

Pumpkins are a fall staple. The plump, round fruits are displayed in autumn decor, carved into jack-o’-lanterns and made into soups and pies. But there are a few pests and diseases that can spoil the fall fun for gardeners. Knowing how to spot these problems early on can make a big difference when your pumpkin harvest comes around.

Downy Mildew

Downy mildew is caused by a fungus that usually shows up on pumpkins in late August or September. Downy mildew causes yellow spots on leaves that can coalesce and turn brown as the fungus grows and takes over more of the plant. You may see fuzzy spores on the undersides of leaves. The spores are spread by wind, so they can easily infect other pumpkins, squash or melons growing in your garden. Purdue University Extension suggests using contact fungicides containing chlorothalonil and maneb at the earliest sign of infection.

Bacterial Wilt

Caused by the bacteria Erwinia tracheiphila, bacterial wilt is spread by the cucumber beetle. While pumpkins are only occasionally infected, the bacteria can be devastating to a crop is exposed. Bacterial wilt clogs the plant’s vascular system so water and nutrients can’t get where they need to go. The vines will wilt and eventually turn brown and die. Controlling the cucumber beetle is the best way to prevent the spread of bacterial wilt. Use pesticides containing carbaryl, methoxychlor or diazinon. If a plant does become infected, pull it up but leave it in the garden and allow it to dry out. Untangling the plant from its healthy neighbors may damage them.

Alternaria Blight

Warm, wet weather favors the spread of alternaria blight. Caused by the fungus Alternaria cucumerina, it causes targetlike brown-to-black spots on leaves and, occasionally, soft spots on pumpkins as well. Eventual defoliation and death of the plant will occur. The fungus over winters in pumpkin debris from previous crops so be sure to clear your garden of refuse each year. Use fungicides thriam and captan to control spread of the fungus.

Insect Damage

Spider mites, squash bugs or whiteflies can all cause brown or yellowed leaves. Spider mites will leave a fine webbing on plants along with spotted yellow leaves. Whiteflies hide on the undersides of leaves and you’ll see them fly up in clouds when you touch the plant. They turn leaves yellow with spots of sooty mold. Squash bugs are small flattened, beetlelike insects that leave yellow spots on leaves. These spots will eventually turn brown and leaves will begin to wilt. Insects can be controlled by insecticidal soaps or pesticides but these methods can also harm bees which are critical to pollination. Spider mites and whiteflies can be controlled by regularly washing plants with water. Gently spray undersides of leaves with the hose daily and you’ll be able to keep them in check. Squash bugs can be trapped at night under boards. In the morning turn the boards over and kill the bugs. You can also pick young bugs and egg masses off your plants to prevent the population from increasing.

Plethora of problems plaguing pumpkin plants

Question: Can you please help with my pumpkins? Every year they do great and get flowers on them, and then all of a sudden something gets them. The leaves start to wilt, turn brown, and completely shrivel up. I can crinkle them in my hand. Then the pumpkin plants end up dying. The garden center says to use a chemical pesticide, but I don’t want to. I tried an insecticide soap and an organic bug spray but nothing works. What causes this? Thank you.

Answer: There are two different issues your pumpkin plants could be facing that are likely to cause the type of damage you describe. The first is a fungal pathogen, and the second is an insect. It’s also possible that your plants are being affected by both of these issues simultaneously, making the damage even more significant. Let’s talk about each issue in turn.

Powdery mildew is a fungal issue that often affects pumpkin plants, though when it’s the only ailment the plant is facing, it seldom outright kills the plant; it just makes it look not-so-hot. But, if a plant comes down with powdery mildew and it’s left uncontrolled, the infection will weaken the plant and make it more prone to attacks from insects and other pathogens. The primary sign of a powdery mildew infection is a white, dusty covering over the tops of some or all of the leaves. Eventually, infected leaves will turn brown and crunchy and die.

The best way to fight powdery mildew is to plant only naturally resistant pumpkin varieties at the start of the gardening season. Selections like “Early Giant,” “Racer Plus,” Rival,” and “Charisma” show great powdery mildew resistance and are available from some local nurseries as well as from online seed purveyors such as Johnny’s Selected Seeds (johnnyseeds.com).

Once a powdery mildew infection settles in, it can be tough to eliminate. But it’s perfectly possible to slow the spread of this fungal pathogen with biofungicides, such as Serenade™, and bicarbonate-based fungicides, such as GreenCure™. Both are safe to use on organic gardens.

The insect pest that could also be responsible for your pumpkin plant woes is the squash bug. This half inch to inch-long true bug sucks plant juices from the leaves, leaving them mottled and weakened.

Eventually, the leaves turn brown and die as you describe.

Squash bugs are hard to miss. Bronze-colored eggs are laid in clusters on the undersides of pumpkin and squash leaves. Squash bug nymphs are tiny, sway-backed, gray insects that feed in large groups on leaf undersides, along stems, and at the stem-end of the fruits. As they grow, the nymphs turn brown and increase in size. When squished, they have a distinctive, foul odor.

Controlling squash bugs is a feat that’s easier said than done. Because of the way they feed (with a needle-like mouthpart), they are resistant to most pesticides that have to be ingested to be effective. Applying insecticidal soap to the actual insects is effective, but difficult to do. If you can, search the leaf undersides every few days and use a piece of sticky duct tape to lift the egg clusters from the plants and then dispose of them.

You should also cover the plants with a lightweight floating row cover from the time of planting until the plants come into flower. This protects the plants from the insects when they’re young and most vulnerable to damage. Remove the row cover when the vines come into flower to allow access to pollinators.

Young squash bugs that are still in the nymph stage can also be targeted with organic pesticides based on Neem oil, but once these insects have reached maturity, they are very difficult to control.

Horticulturist Jessica Walliser co-hosts “The Organic Gardeners” at 7 a.m. Sundays on KDKA Radio with Doug Oster. She is the author of several gardening books, including “Attracting Beneficial Bugs to Your Garden: A Natural Approach to Pest Control” and “Good Bug, Bad Bug.” Her website is jessicawalliser.com. Send your gardening or landscaping questions to [email protected] or The Good Earth, 622 Cabin Hill Drive, Greensburg, PA 15601.

  • TribLIVE’s Daily and Weekly email newsletters deliver the news you want and information you need, right to your inbox.

    Yellow Leaves on a Pumpkin

    sergio_kumer/iStock/Getty Images

    When growing pumpkins (Cucurbita maxima varieties) in the home garden, the sight of yellowing leaves can jar gardeners used to enjoying sprawling green foliage and deep orange fruit on these annual vines. Yellowing leaves signal something amiss with your pumpkin crop, and can be caused by several different factors. Prompt action and the right diagnosis can help you limit damage to your pumpkins and get your harvest back on track.

    Doube-Checking Care

    Appropriate care for your pumpkin vines is essential to a good crop and green leaves. Healthy pumpkins have a greater likelihood of avoiding and recovering from pest and disease issues that affect these well-known squash. Grow pumpkin vines in areas that provide full sunlight for best development. Maintain moist, well-drained soil with pH levels between 6.2 and 6.5 for best growth. Pumpkins need irrigation, though overhead watering can contribute to problems with fungal disease. Water soil directly through methods like drip irrigation. Irrigate to a depth of 6 inches for moist, but not saturated, soil.

    Balancing Nutrition

    When care is under control, nutrient deficiency may be behind yellow pumpkin leaves. Even when compost is generously mixed in the garden before planting, pumpkins often need extra nitrogen. Incorporate compost or a 5-10-10 granular fertilizer at planting at a rate of 1 to 2 tablespoons per plant. One week after pumpkins blossom, add a high-nitrogen fertilizer such as 33-0-0 ammonium nitrate at the rate of 1 tablespoon per plant. Repeat that application again in three weeks. Wear gloves and safety goggles when working with chemicals, and water the area well after your applications. A soil test helps confirm any other possible nutrient problems.

    Managing Mildew

    Powdery mildew is a common pumpkin disease caused by fungal infections. During warm weather, powdery mildew starts with yellow leaf spots that grow into yellowed, dying leaves. A powderlike fuzzy growth also develops on leaves, as the name suggests. To prevent powdery mildew on pumpkins, keep the area surrounding your pumpkins free of weeds, and avoid overhead irrigation. Water in the mornings, so leaves dry by nightfall. Never work with your pumpkins when foliage is wet, and keep all equipment sterilized with household disinfectant to prevent disease spread. If mildew is severe, apply a ready-to-use horticultural oil spray to control further spread. Never use oils on drought-stressed pumpkins or with temperatures above 90 degrees Fahrenheit.

    Beating Borers

    Squash vine borers attack pumpkins with the potential for severe damage. Wreaking havoc as cream-hued, brown-headed larvae measuring approximately 1 inch in length, these pests bore into pumpkin vines. Boring inhibits the water and nutrient distribution throughout the plant, leading to wilting, yellowed leaves and plant death. Prevention and intervention are key to control. Cover pumpkin plants with row covers as soon as you notice squash borer activity. If you’ve had past problems, do it right after planting. Destroy all affected vines and plants and dispose of the infected debris. Plant pumpkins in different areas each year. A ready-to-use pyrethrum spray can help control damage. Spray leaves thoroughly so the pests contact the spray.

    Why Are My Pumpkin Plant Leaves Turning Yellow?

    Pests, poor soil quality, nutrient deficiencies and age can cause the leaves of a pumpkin to turn yellow. Mature vines may have yellow leaves soon after pumpkins ripen.

    Pumpkin vines should be treated for squash bugs and squash leaf borers if leaves are turning yellow and then browning along the outer edge. Squash bugs can be eliminated using a commercial pesticide applied right before dusk to prevent harming beneficial insects.

    Pumpkin leaves begin to yellow when the soil does not contain enough nitrogen. Treating the soil with additives boosts nitrogen levels. Using a drip system or spraying water directly on the base of the plant ensures the plant has access to necessary moisture.

    Rotating crops prevents problems, such as fusarium wilt, that may cause pumpkin leaves to yellow prematurely. Diseases that are related to poor soil caused by lack of rotation also include phytophthora and rhizoctonia. These issues can be prevented by starting seedlings in a different area of the garden each year and treating soil for nutrient deficiencies before planting.

    Mature pumpkin vines that have produced full-sized, healthy pumpkins will naturally start to decay as the season progresses. If the vine is also yellow and pumpkins are ripe, the best choice is to remove the pumpkins and allow the vine to shrivel.

    Sep 13, 2017Decoding the cause of yellow pumpkin leaves

    This time of year, I receive many complaints of pumpkin plants with yellow leaves. There can be many reasons why pumpkin plants have yellow leaves. The most common reason for yellow pumpkin leaves doesn’t have anything to do with a disease that can spread from plant to plant. Usually, the reason for the yellow pumpkin leaves has to do with lack of water, weather that has been too hot, nutrient deficiency or other stresses. The photos and discussion below will, I hope, illustrate my point.

    Let’s say you have a pumpkin field where you have pumpkin leaves that are yellow and you are wondering about the cause. You may want to ask yourself, which leaves are yellow and where are they yellow.

    In Figure 1, yellow pumpkin leaves may be observed. When one looks a bit closer to find out where the yellow leaves are, one can see that the yellowing runs down the row. In fact, it is the older leaves that are yellow (Among plant biologists, we prefer the term chlorosis to yellow. But I will continue to use the word yellow here.) When older leaves are yellow and the younger leaves appear green and healthy, the reason for the yellowing is usually stress-related, as indicated above. I am not too worried about this type of yellowed pumpkin leaves.

    Figure 1. The yellowing of these pumpkin leaves seems to run down the row.

    Look again at figure 1 to try out which part of the leaves are yellow. For the most part, the portion of the leaves that are yellow are the edges (or margins) of the leaves (Figure 2). One doesn’t see entire leaves that are yellow. The yellowing doesn’t appear in the interior of the leaves. Yellowing on the outside of the leaf normally means that the reason is stress related as discussed above.

    Older leaves tend to become yellow with time because nutrients like nitrogen are mobile in the plant and will move to the younger leaves where they are needed. In addition, the edges of leaves may become yellow because the edges of leaves have pores where sap (known as the water of guttation by botanists) is secreted at night. This sap may have a mildly toxic effect on the leaves over time—this is the reason that the edge of older leaves may become yellow.

    Figure 2. The edges of this pumpkin leaf are yellow, most likely due to environmental stress.

    In figure 3, the yellowing of the pumpkin leaves is more generally over a larger area in contrast to figure 1 where the yellowing could be seen to run down a row. Most of the yellowing appears in the foreground of the photo in figure 3. If one looks down the hill, the leaves appear green and healthy. Now, let’s look at the soil next to the symptomatic pumpkin leaves. The soil appears sandy.

    Next, we will walk down the hill where the pumpkin leaves are green and look back up toward the yellowed pumpkin leaves (Figure 4).

    Figure 3. This view is from the top of the hill looking down. The pumpkin plants in the foreground of this photos have yellow leaves. The soil is sandy at the top of the hill.

    Again, we notice that the area on top of the hill is in a general area—they don’t seem to run down a row. That is, it isn’t just the older leaves that are yellow. Now, take a look at the soil next to the green pumpkin leaves at the bottom of the hill. The soil is much heavier with more of a clay content than the soil at the top of the hill.

    Figure 4. This view is from the bottom of the hill looking up. The pumpkin leaves at the bottom of the hill are generally green and healthy. The soil at the bottom of the hill is relatively heavy.

    The lesson here is that the pumpkins at the top of the hill had much less access to water than the bottom of the hill. This is true both because hills tend to be better drained and because sandier soils hold less water. The grower had drip irrigation in place, but was not able to pump much water due to lack of water in a surface pond. Therefore, the yellowing leaves at the top of the hill are due to drought stress.

    Both of the fields of pumpkins pictured here produced good crops. The yellow on the pumpkin leaves does not necessarily indicate a disaster or a disease is in the future.

    I hope the photos and discussion presented here will help one to figure out what is wrong in one’s pumpkin patch. However, if one still has questions about symptoms, it is best to send off a sample to a diagnostic laboratory. Purdue University’s Plant and Pest Diagnostic Laboratory is an excellent resource

Leave a Reply

Your email address will not be published. Required fields are marked *