Nutritional disorder – magnesium (Mg) deficiency
Older leaves initially develop a marginal leaf chlorosis which later progresses to a tanning or darkening coloration along the outside leaf margin. As symptoms develop further, the interveinal chlorosis expands inward on the leaf and the dark discoloration spreads between the veins. With advanced symptoms, the entire leaf can become necrotic. In addition, fruit color appears pale, but fruit size is normal.
Potassium deficiency, sodium toxicity, drought stress, and wind damage may produced similar symptoms.
Because symptoms can occur due to many possible causes, it is important to determine the actual cause. Tissue testing will help identify any nutritional disorders. Reviewing the weather history and growing conditions will help to determine if that is the cause. It is also useful to note that weather related problems will be more prevalent over a wider area of the field and will develop quickly. Nutrient deficiencies usually take weeks to develop.
Take a soil sample to determine if nutrient levels are inadequate. Submit a leaf sample for nutrient analysis. The sufficiency range for magnesium in strawberries is between 0.25 and 0.5%. Values below 0.25% are considered deficient and above 0.5% are considered excessive.
Take a soil and tissue test to determine nutrient levels. Make adjustments based on those test results and the lab’s recommendations.
Conduct a soil test prior to planting the crop to determine if pre-plant fertilizer applications are required. Fertilizer can also be injected to the crop during active growth. Recommendations vary by soil type and your location, so check with local resources for guidelines.
Funding was provided in part by the National Sustainable Agriculture Program: Sustainable Strawberry Initiative and the following sources.
A thank you is also expressed to Kube Pak of Allentown, New Jersey for donating strawberry plants.
Publication date: April 24, 2014
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