Iron Chlorosis
Yellow leaves with green veins on blueberries
- Iron chlorosis is common in blueberry plantings and, if left untreated, will cause decreased growth, yellowing foliage, early defoliation, and severely weakened plants.
- The characteristic foliar yellowing may be apparent early in the spring or can develop later during the summer.
- Symptoms develop because iron is not available to the plant, even though this element is fairly abundant in most soils. When the yellow foliage symptoms develop early in the spring, the soil pH is usually too alkaline (above pH 6). When the yellow foliage develops during the summer, soil temperatures for these shallow-rooted plants may be too high.
Management of iron chlorosis
- It is advisable to test and prepare the soil 6 months before planting blueberries. Proper site preparation greatly reduces the chance of iron chlorosis.
- The problem can be alleviated temporarily by spraying the foliage with a chelated iron formulation available at most garden stores, but more permanent measures are needed to keep plants vigorous and productive.
- Where soil pH is too high, sulfur and iron sulfate can be incorporated into the soil to acidify it so that iron will be more available to plant roots. Where high soil temperatures seem to be the problem, a 3-to 4-inch layer of sawdust will retain water and insulate the topsoil against overheating.