If you grow peas or lentils, you should know about pea seed-borne mosaic. The same is true for fava beans and chickpeas.
[Sadly, I was unable to find any freely available photos of pea seed-borne mosaic, so you will have to go by the description or search for your own images. The purple-podded peas pictured above are perfectly healthy.]
Symptoms of pea seed-borne mosaic
Stunting, deformation, and rosette-type growths at the ends of stems are all signs of pea seed-borne mosaic. Chlorosis, downward cupping, vein clearing and swelling, and the classic mosaic or mottling of mosaic diseases may all be present in infected plants. Vein clearing is a common symptom of viral infections and it refers to the way leaf veins appear translucent. Seeds tend to be shriveled and discolored. Infected plants are slow to reach maturity, but don’t leave them in the ground long enough to notice. Pea seed-borne mosaic infection is easily mistaken for chemical overspray, nutrient toxicities, and water-stress. Laboratory tests are needed to be sure of infection. You can often take zip-lock bagged samples to your local Department of Agriculture for analysis.
How to control pea seed-borne mosaic
The pea seed-borne mosaic virus (PSbMV) is carried to your garden on aphids. I would tell you to control the aphids, but that is an ongoing battle in the garden. Do the best that you can. Plants infected with pea seed-borne mosaic should be removed immediately. Unfortunately, some infected plants will never show symptoms. As aphids feed on these asymptomatic plants, they then carry the disease to nearby plants, spreading infection. For the most part, as the name implies, this viral disease is carried by infected seeds. Plant infected seeds and the aphids do the rest. To prevent pea seed-borne mosaic from occurring in your garden, only buy clean, disease-free seeds.
This disease can overwinter in nearby weeds, such as shepherd’s purse, vetches, and black medic. It can also be carried on alfalfa and sugar beets without causing the host plants any problems. If you notice outbreaks of pea seed-borne mosaic, and you know your seeds were clean, look at what is growing nearby.
You can prevent pea seed-borne mosaic by planting resistant varieties.
You can grow a surprising amount of food in your own yard. Ask me how!