By: Amy Grant
As with any plant, pea plants need sun but prefer cooler temperatures for truly bumper crops. Relatively easy to grow within these parameters, there are several things that notoriously afflict them, causing yellow leaves on pea plants. Should your pea plants yellow at the base and are looking generally unhealthy, or if you have a pea plant turning yellow and dying altogether, I’m sure you are wondering why and what can be done.
There are several possibilities to answer the question, “Why is my pea plant yellow?” Fusarium wilt, root rot, Ascochyta blight and downy mildew are all fungi that may afflict these crops and result in the yellowing pea plants.
Fusarium wilt – Fusarium wilt causes the yellowing of pea plants’ foliage, stunting and wilting of the entire plant. The base of the stem, however, is not affected. The fungus lives in the soil and enters through the roots of the pea plant. There are Fusarium resistant varieties of pea that will be marked with an F, which is advisable to plant if this seems to be an issue in your garden. Crop rotation and the removal and destruction of infected plants are also deterrents to Fusarium wilt.
Root rot – Root rot is also a soil borne fungi that affects peas. Pea plants yellow at the base of the plant, stems wither and eventually die back. Spores are dispersed through contact, wind and water. The fungus overwinters in garden debris, waiting to afflict new plants in the spring. Preventative measures for root rot are to plant in well draining soil, avoid over watering, rotate crops, allow adequate space between plants, purchase disease free seeds and/or those treated with a fungicide and remove and destroy affected plants.
Downy mildew – Downy mildew causes other discoloration, but also shows as yellowing lesions on pea plants with a gray powder or mold on the underside and dark spots on the pods. To eradicate this fungi, air circulation is of most importance. Rotate crops every four years, maintain a debris-free garden, plant resistant seeds and remove and destroy any infected plants.
Ascochyta blight – Lastly, Ascochyta blight may be to blame for a pea plant turning yellow and dying. Yet another fungal disease and made up of three different fungi, it over winters in plant debris or enters the garden in the spring in infected seeds. Rain and wind in the spring serve to spread the infection to healthy plants. Symptoms of Ascochyta blight vary depending upon the fungus causing the infection, anywhere from stem blackening, bud drop, and yellow or brown spots on foliage. To manage Ascochyta blight, remove and dispose of infected plants, rotate crops yearly, and plant commercially grown disease-free seeds. There are no resistant cultivars or fungicides for Ascochyta blight.
Most causes for yellowing pea plants are fungal and the management of all of them is pretty much the same:
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Peas (Pisum sativum) are a great addition to any garden, especially in zones 2 through 9, according to the Old Farmer’s Almanac. Once established, they need very little attention and will happily grow along a support or sweet pea trellis until harvest with few pea plant problems.
Peas thrive best with light but frequent watering in good sun. Peas can be eaten right off the vine or gently steamed or stir-fried into a number of meals. While they’re easy to grow, pea plants can still suffer from aggressive weather or diseases that will affect growth. Keep an eye on the entire garden to make sure the plants stay healthy and strong.
The best way to deal with problems is to avoid them in the first place. Here are some suggestions about how to prevent disease and insect problems in your garden before they even begin.
In the North, aphids and pea weevils are the most prevalent insect pests, wheras in the South the primary pest is the cowpea curculio. Blight, fusarium wilt, mosaic virus, powdery mildew and root rot are the most common diseases of peas.
Keep a careful watch over your garden. If problems arise, contact your extension service. Your local extension agent can advise you about how to deal with specific garden problems you may have.
The following guide will help you decide what problems may be bothering your crop.
Bacterial blight is a disease carried on infected seeds. Large, water-soaked spots appear on pea pods and irregular dark spots appear on leaves cream-colored, shining ooze appears in the center of these spots. To avoid blight, plant certified disease-free seed on well-drained soil. Remove old pea vines and rotate your crops.
Cowpea curculio, a destructive southern pest, eats holes in peas and pods. To control, spray or dust with a registered pesticide.
Pea aphids are pear-shaped, long-legged, soft, green insects only 1/16 to 1/8 inch long. By sucking juices from the leaves and stems, they may cause withering of plants and stunting of crops, thus reducing yields.
Control aphids by gently rubbing them off leaves or spray infested areas with an insecticidal soap. Ladybugs and aphid lions are naturally occurring enemies that may be in your garden.
Pea weevils are microscopic pests that lay their eggs on developing legume seeds, on which the larvae then feed. Infested dry peas will be riddled with holes and small worms within weeks of storage. Reduce weevil problems by planting early and turning the plants under right after harvest. For best storage results, spread dried peas on a cookie sheet and place it in a 175oF oven for one hour. When cool, bag and freeze the peas for a week, then store them at room temperature.
Damping-off fungi, which cause seed decay, are prevalent during cool, moist weather. To avoid this problem, plant only after the soil is dry enough to work easily.
Fusarium wilt causes pea leaves to turn yellow. The plants are stunted and eventually wilt. Fusarium wilt symptoms are similar to those of root rot. The main difference is that the base of the stem of a plant affected with wilt isn't withered, and the inside of the stem shows discoloration. This fungus lives in the soil and enters the plant through its roots. Check seed catalogs or seed packets for resistance to the disease. Fusarium-resistant varieties will be marked with an F. For other control measures see root rot.
Mosaic virus is spread by aphids and carried within infected seeds. The plants usually become stunted, leaves turn light colored and mottled, and pods are few and poor in quality. To reduce infection, remove pea plants that show leaf mottling and control aphids.
Powdery mildew is a fungal disease that's most troublesome in warm weather. A white or grayish powdery mold appears on the pods, leaves and stems. To combat this problem, turn under or compost the pea vines as soon as the harvest is over, water in the morning only and plant resistant varieties.
Root rot is caused by soilborne fungi that often kill plants at flowering time. Plants turn pale yellow and may be stunted. The stems wither near the ground, and the plants often die back or collapse. To avoid root rot, plant peas in well-drained soil. Remove and destroy affected plants. Rotate crops.
If you choose to use commercially available sprays or dusts, purchase the least-toxic preparation that will do the job effectively.
When using a commercial spray or powder, read the instructions three times: before buying to make sure you buy the right substance before using to be sure you use it correctly and again before storing in order to put it away properly.
It's often best to contact your local extension service for advice when a problem arises. Not only can extension agents help you to identify the unwanted pests in your garden, they'll also suggest the best remedy for dealing with them in your area.
Peas do like to grow in colder weather than other crops, but they do need the soil to be a certain temperature in order to germinate. The soil needs to be at least somewhere around 45 degrees for germination. Since germination has been slow, the amount of rain we have gotten most likely caused my friend's peas to rot.
Subsequently, question is, how do you treat root rot peas? Treatment and Preventative tips:
Hereof, do peas keep producing?
Peas will produce as long as vines are healthy and temperatures stay cool. Mulching soil helps keep roots cool. Once the temperature reaches the 80s, pea season is over. The more you pick peas, the more peas you'll have to pick.
How much water does a pea plant need?
Growing Peas Planting depth should be roughly 2 inches with a spacing of about 2 inches apart. Water well at planting and provide at least 1 inch of water per week, particularly during the flowering and pod production stages. As the temperature rises, the vines may need to be deeply watered almost every day.
Wet and cool weather cause pea plants to appear yellow in colour in early spring. This is not caused by any type of disease and is normal under such conditions. These yellow pea plants will darken and turn green as temperatures rise and the soil dries out. Pea plants grown in this type of weather are at greater risk of developing other conditions, especially fungal diseases. Observe your plants closely, looking for other signs of disease such as wilting, curling of leaves or stunted growth to determine if the yellow discolouration is due simply to weather conditions.