Roses can be affected by a variety of pests, diseases and other conditions. Winter is a good time to begin taking some preventative action.
1. Rose aphids
Rose aphids are common insect pests that often attack roses. As sap-suckers, they usually prefer flower buds, and can cause serious damage to flowers. Sooty mould may grow on the honeydew they exude. Other aphid species may also attack roses.
Look for
Clusters of tiny insects on flower buds, and sooty mould. The first aphid flight occurs as the weather warms up.
Action
Squash aphids between thumb and forefinger. Try hosing rose aphids off or use an insecticidal soap spray or an approved systemic insecticide such as imidacloprid. Encourage the natural enemies of aphids by minimising the use of toxic chemicals on roses.
Two-spotted mites are also sap-sucking pests, which can cause a distortion of flowers and growing tips, as well as leaves drying up on the plant.
Look for
Discoloured and mottled leaves and fine webs forming on the foliage.
Action
Remove and dispose of severely infested shoots and leaves. Use sulfur, horticultural oil or insecticidal soap. Following label instructions, apply lime sulfur in winter. Release commercially available predatory mites during spring.
3. Balling
Balling is a condition most often caused by tender buds becoming wet during the heat of the summer months.
Look for
Petals that stick together. As they dry out, the outer petals form a dried cocoon from which the flower may not burst. The flower inside may rot and the bud could eventually fall off. Severe attack from thrips can look similar, but the bud will usually open into a distorted and browned bloom.
Action
In both cases the buds should be removed. To prevent balling, don’t wet buds when watering, especially during extreme hot weather.
4. Powdery mildew
Powdery mildew is one of the most widespread garden plant diseases, and is common during humid weather. It is more prevalent in younger stems and leaves. A bad attack can distort tips and spoil flowers. Infection may be spread by wind and rain.
Look for
White powdery fungal growth spread over the upper surfaces of leaves.
Action
Don’t wet leaves when watering. Prune infected leaves and put them in your rubbish bin. Prune roses to improve air circulation. Apply a winter spray of lime sulfur to prevent fungal infection, and also kill overwintering mites. Spray infected roses during the growing season with a registered synthetic fungicide or a copper-based fungicide.
Black spot is a fungal disease that attacks leaves and sometimes young stems. It is favoured by humid, warm conditions such as in late spring and early summer. The tiny spores can also overwinter in infected leaves and stems.
Look for
Fringed dark brown or black spots on leaves, initially low down on the plant; and yellow leaves and defoliation.
Action
Don’t wet leaves when watering. Prune and dispose of infected leaves in the rubbish. Prune roses to promote air circulation, and rake up infected leaves. Disinfect secateurs if plant is infected. Try an organic copper-based fungicide, or a registered synthetic fungicide.
2013 Bedding Advertisements: If you want to decor your bedroom in 2013 brand new spring style or if you are seeking for some 2013 bedding sets for you and your family, Bedding US here offers brand new 2013 luxury bedding sets to meet all your needs. Various styles and patterns are available for you.
No comments:
Post a Comment