Rows of pumpkins in a field or hill are beautiful. For a farmer or gardener that’s a source of pride. And when the fruits start appearing, one knows that halftime is reached.
Harvest time is around the corner but the owner notices a nasty yellowing. A thought crept in like weeds on a bad day. All my pumpkin plants will turn yellow!
Okay, leaves yellowing are actually common, and sometimes they don’t have to cause harm. Even so, what should you do in this situation?
Reading this article will inform you on the causes of yellowing, and what actions to take. Growing plants take diligence and patience. As you read on, you’ll get ideas about what steps to take. (Read Cucumber Yellow Leaves What to Do)
Growing Pumpkins
Before we delve into the causes of yellowing let’s take a closer look at how pumpkins grow. It’s okay to skip this short part. Its usefulness comes only when you need to know the basics.
Pumpkins come in a lot of varieties. But they all need several hours of full sun, lots of water, and well-drained soil.
They are not hard to grow, and you can plant the seeds indoors. But a pumpkin plant needs lots of space soon after.
What Pumpkin Plants Need:
- A big space for their vines is needed. Some varieties will require more than others though. Just make sure to leave a wiggle room for their vines to expand when planting in raised beds.
- About 8 hours of direct sunlight is preferred for growing pumpkin plants . They are sensitive to cold temperatures so make sure to stay in an optimal range. Somewhere between 65 and 95 degrees is best.
- The soil must be rich with pH level neutral. Loose and loamy is what they want. Also, rich means layers of compos and other goodies for plants.
- They need a lot of water, and a moisture depth of 6 inches is good. Pumpkins also want their soil to have a good infiltration.
- They need lots of water but they want to stay dry. The leaves get damaged when soaked in water.
- Pumpkins generally take 10 days to germinate. And about 90-120 days to mature. After being flowered a pumpkin matures in 50 days.
2 Main Reasons for Yellowing
We can categorize the causes of yellowing into two groups. The most common reason for pumpkins to turn yellow is stress. The other reason is because of pests and fungi.
A more technical word for yellow is chlorosis.
Condition Based
These are the stress-related causes of yellowing. They are easier to handle considering you could make adjustments.
1. Too Much Sun
The Earth’s getting warmer, and the weather’s sporadic. It’s more common for hot spikes to occur . And if it’s consistently above 100° F of for days it would cause leaves to turn yellow.
More water, and some mulch, is the key.
2. Imbalance of Nutrients or Nutrient Deficiency
Pumpkins need some nitrogen. n. It’s common for yellowing to occur if there is lack of nitrogen. And it’s common for sandy soil to lose nitrogen quickly. (Learn What Type Of Fertilizer To Use In Spring)
Planting legumes or beans helps in retaining nitrogen. Adding mulch or fertilizer is a great idea. There’s several more things you could consider like:
- Using fish emulsion
- Giving heaps of organic matter
- Mixing coffee grinds
We covered one out of the three most important nutrients. Let’s proceed to P and K. There’s nothing much to it-just use fertilizers and such. Their nutrient need is larger than most garden plants so be sure to crank it up in that area.
Also, too much nitrogen can lead to a pumpkin yellowing. Be sure to use a test kit when in doubt. Lack of Magnesium and Iron also causes chlorosis.
3. Lack of Water
More often than not, the reason why pumpkin plant leaves turn yellow is because of lack of irrigation. Naturally, you would want a pond or nearby source of water. If that’s not the case then constant watering is needed.
A pumpkin need around an inch of water every seven days. But make sure to keep the plant itself dry. Water before the morning sun rises high or in the evening.
Additionally, lack of water also causes wilt. Wilting and yellowing of the leaves are a probable sign of dehydration.
4.Lack of Light
Sometimes it could be as simple as shade. A pumpkin need a lot of light. And while some can survive being shaded most will show yellowing if lacking full sun for 8 hours a day.
Diseases
A pumpkin plant is susceptible to many diseases. A yellow pumpkin could be just experiencing stress but disease is not out of the question. Best to investigate, and make informed guesses.
Insect vectors spread virus or bacterial infection (bacterial wilt). Fungi typically arises if the conditions are bad.
The following diseases are a few that affect the pumpkin plant. Some of these might apply to other cucurbits. Squash, melons, cucumbers are some examples of cucurbits.
Watering and application of nutrients must be done correctly.
Yellow Vine Diseases
Ohio farmers had been hit with yellow vines diseases way back in the early 2000′. But on 2008 it was hit hard. The Ohio State University Extension states that yellow vine causes yellowing, and death.
Their advice when determining the disease is to slice at the stem base. Then probe at the vascular tissue, and to look for a hone-brown color in the tissue. Squash bugs are the culprits
Downy mildew
The oldest leaves gets yellowish brown spots first. After some time leaves curl and die. Typically, happen when your squash get wet a lot and is plant in a warm region. (Learn How To Get Rid Of Powdery Mildew On Squash)
The key methods in preventing a fungal borne diseases in a pumpkin are the following:
- Crop rotations
- Removal of crop debris
- Insecticides
- Keeping the squash plant dry
- Specific Parts of an infected pumpkin plant should be removed
Aster yellows
The leaves turn yellow, and flowers are affected badly. Your only hope is to spot the infected plant, and remove it quickly. Hundreds of plants are affected, not just asters. Leafhoppers are the vectors of the disease.
It affects the entire plant, and yes there is chlorosis. Weeding out plantains is recommended as they are prime targets of leafhoppers. Also, add barriers to your pumpkin patch so that the leaf hoppers won’t eat them.
When a leafhopper eats from an infected plant, they get infected quickly. Also, your plant doesn’t die when they get asters yellow, unlike bacterial wilt.
Natural Process
Sometimes, it’s natural for your leaves to change color. When the pumpkin fruits are mature the leaves turn yellow.
Pests
Sometimes, the pest themselves are the cause of yellowing. They don’t have to carry bacteria or viruses. There are many more pests out there that can cause pumpkin leaves to yellow.
Squash Bugs
They lay conspicuous eggs, and are often mistaken for stink bugs. Use insecticides, and destroy all plant debris in your pumpkin patch. Also, use mechanical covers to thwart these pests.
Squash Bugs are common, and younger plants are more vulnerable to it.
Aphids
They cause chlorosis if large numbers are concentrated on a small area. Get rid of these pets with insecticides, and deter them with row covers.
Aphids are small sap-sucking critters. They have different characteristics.
Wrap-up
There are many reasons why leaves turn yellow. Some are easier to deal with, while others are dangerous. The causes can be divided into two major categories: stress-related or biotic.
There are preventative measures you can do to biotic causes. To ensure plants don’t yellow because of stress make the conditions excellent.
Thanks for reading. Have a successful growing season!
