Zinc Deficiency in a Strawberry Plant

Symptoms

• Zinc deficiency is most likely in sandy soils that are low in organic matter. If your strawberries are suffering from zinc deficiency, you'll start to see green margins or halos along the edges of young leaves. The blades of these leaves will become thinner and narrower at the base as the leaf grows; the leaves will turn yellow, and the number of fruit per plant will decrease even if the average size of each fruit remains normal.

Levels

• The ideal zinc concentration in the leaf tissue of your strawberries is about 35 parts per million; levels in the 20 to 50 parts per million range are normal. Levels below 20 parts per million warrant the addition of zinc and possibly action to correct the soil pH. If you suspect a deficiency, you can take samples of leaf tissue from your plants and send them to a laboratory for testing. Many university agricultural extension programs offer these kinds of tests for farmers and gardeners; check with your local institution to determine whom you can contact for more information.

Soil and Application

• Test the soil rather than the plant tissue if you prefer; your area's university ag extension service will provide a soil test. Get a test kit, which is rarely more than an instruction sheet and a cardboard box, and fill the box with soil, following the instructions carefully. If the soil sample was collected from the top 12 inches, you shouldn't have a zinc reading below 0.5 parts per million. If you find that your soil or plant tissue is deficient in zinc and exhibits the usual symptoms, find a fertilizer blend that contains zinc sulfate or zinc chelates. You can also use leaf sprays that contain zinc, but these carry the potential to damage immature leaves and fruit.

Considerations

• Soil pH is an important consideration you should bear in mind. If the pH is too high for your strawberries, they will be unable to obtain the zinc they need -- although they exhibit symptoms of zinc deficiency, the pH is the real problem. A soil test can determine whether your soil is too alkaline for your strawberries. If this does indeed turn out to be the case, don't apply more zinc -- it won't help. Try switching to fertilizers that will reduce the soil pH like ammonium sulfate instead. But be sure not to overdo it -- an overly acidic soil can cause problems for your strawberries, too.