Yellow Leaves on My Roses - Part 2
bloom buds may be distorted.
Zinc toxicity can occur when too much millorganite or houorganite treated sludge is used as a soil amendment or fertilizer.
Phosphorus toxicity
Phosphorus toxicity is becoming an increasing problem in areas where its overuse has accumulated in clay-based soils. This is particularly important to rosarians who frequently succumb to the media hype and apply water soluble, high phosphorus fertilizers in hopes of achieving bigger blooms.
Phosphorus toxicity displays the same symptoms of nutrient deficiencies - copper, iron and zinc. That is, leaf tissues yellow while the leaf ribs remain green. Leaves may become thicker than normal, but appear on shorter stems. Buds may become irregularly shaped.
The reason for this is because too much phosphorus makes these three elements unavailable to the plant.
Potassium toxicity
Potassium toxicity appears the same as phosphorus toxicity, and for the same reasons. The chief difference is that too much potassium also manifests in root loss and consequently the wilting of tender new growth.
Treatments for too much "love" - that is, too many nutrients - is to reduce the amount of fertilizer applied. In some areas of the country, many gardeners do not have to add any phosphorus to their fertilizer mix, for example.
Next time, we'll look at the pests and diseases that can cause yellowing leaves.