Pests and Diseases of Roses - Environmental Disorders

Environmental Disorders

• Frost will destroy fresh growth causing stems and leaves to wilt, turn black and fall away from the plant. Timing pruning to promote growth after the threat of frost is a means to avoid frost damage.

• Salinity will present in roses as limp and light brown leaves with dry leaf margins. Soil may require testing to determine salinity levels. Symptoms will present if salinity is greater than 1200 parts per million.

• Herbicide Damage – Overspray or soil leaching of herbicidal sprays can present with several symptoms: :Prolonged exposure to overspray of glyphosate will cause yellow leaves and new leaves will be small and elongated. Hormone weed sprays (e.g. 24-D & 245-T) may cause grotesque new growth with thin twisted leaves and distorted buds. Plants may die in severe cases. Pre-emergent herbicides contacting the plants' root system via the soil will cause yellowing foliage. Effects of soil borne herbicide may take several years to clear.