Caring for Pea Plants with Fungus
Your peas are growing beautifully, putting up springy tendrils and delicate white blooms. You're anticipating fresh peas on your dinner table and then, it happens. Suddenly, your peas aren't looking so good. Maybe the leaves have sprouted disturbing white spots overnight or those beautiful blue leaves have turned blotchy.
The helpless feeling creeps up, and you're wondering what's wrong with my peas? Can I make it better or are they lost? If you're asking those questions you've come to the right place. Peas are a relatively trouble-free crop and are a great first plant for novice gardener, but there are a few of problems to keep an eye out for.
The big three when it comes to peas are pea enation virus, powdery mildew, and root rot.
Pea Enation Virus causes deformed pods like the one above.
Pea Enation Virus
What it looks like:
Your first hint of pea enation virus will be blister-like growths (enations) on the undersides of the pea leaves and on the pods. The leaves will also display splotchy areas of yellow, sometimes the areas will be translucent. The enations can deform the plant and pods to the point you may not recognize it as a pea plant anymore. The virus causes low productivity and possibly premature death.
What do I do?
Pea aphids carry the virus from hosts like clover and vetch, where it overwinters, to your garden peas. Aphids are usually only a problem in warmer weather so be especially vigilant with fall planted peas. If you find aphids blast them off with water, the bug blaster nozzle is perfect for this. You can also hang adhesive traps to catch the aphids before they get to your peas.
If things are getting desperate consider an organic insecticide labeled to control aphids. Before you reach for the Neem, which can kill beneficial insects, consider less aggressive insecticides first, such as Safer Insecticidal Soap or Organocide.
Powdery mildew is especially prevalent in drier climates.
Powdery Mildew
What it looks like:
Powdery mildew shows up as white "powdery" looking spots on the tops of leaves. The plant's tissue under the powder spot can turn black or brown. Black, oval fruiting structures can form on mature spots. Powdery mildew probably won't kill the plant, but it will produce fewer pods. The pods a that are produced will likely have poor flavor and quality. What do I do? Don't over-fertilizer peas. A slow release organic fertilizer works very well. Don't crowd them, make sure they have plenty of air circulation. If you live in a dry area plant resistant varieties like Oregon Sugar Pod II.
Overhead irrigation can stand in for rain and wash the spores off the leaves. You can also apply a biological fungicide like Serenade which is labeled to control powdery mildew. A sulfur fungicide like Safer Garden Fungicide which is labeled to control powdery mildew is another option for powdery mildew control.
There are several types of root rots common among peas. Above is an example of black root rot caused by Thielaviopsis basicola. Photo by: Bruce Watt, University of Maine, Bugwood.org.
Root Rot
What it looks like:
The pea plants will be stunted and leaves will yellow from the base of the plant up. Often there will be grey, brown, red, or black lesions at or near soil level. If you pull up the plant and inspect the roots, especially the tap root, you will see evidence of dacay. What do I do? Any environmental factors that slow down root growth favor root rot pathogens. Avoid planting peas in compacted soil. Soil can be compacted by working the soil when it's wet, so don't plant peas too early. Don't plant them too late either because many root rots thrive when soil temperatures reach 75°F. If possible plant peas when soil temperatures are 65°F or cooler. Practice crop rotation to prevent or avoid root rots. Peas and legumes should be on a five year rotation.
