Lower leaves initially develop a pale green to light yellow (chlorosis) coloration. With advancing symptoms, the light yellow coloration becomes more intense yellow and expands to cover most of lower leaves. Severe deficiencies result in necrotic leaves and leaf drop. Plants appear stunted and leaf size is smaller.
Symptoms of phosphorus deficiency can also result in lower leaf orange to reddish coloration. Impaired phosphorus update may be due to the lack of sufficient phosphorus, cold growing temperatures, water logged soils, or root rot.
Because symptoms can occur due to many possible causes, it is important to determine the actual cause in order to correct the deficiency.
Take a substrate sample to determine if nutrient levels are inadequate. Submit a leaf sample for nutrient analysis. The sufficiency range for nitrogen in helichrysum is between 2.0 and 4.0%. Values lower than 1.9% can lead to deficient conditions. Levels above 4.0% are considered excessive.
An in-house electrical conductivity test utilizing the PourThru or 1:2 method can provide an indirect status of your nutrient supply, in which nitrogen is usually the largest component.
Take a substrate and tissue test to determine nutrient levels. Make adjustments based on those test results and the lab’s recommendations.
If levels are low, provide the plants with a complete fertilizer at the rate of 200 ppm N to increase nitrogen levels. Retest the substrate to confirm levels are within the acceptable range.
Tissue samples were analyzed courtesy of the North Carolina Department of Agriculture – Agronomic Division.
Publication date: March 29, 2015
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