After reading this article you will learn about the major insects, pests and diseases found in roses.
Insect-Pests found in Roses:
White ants:
They attack the plants and damage the root system and slowly plants die completely. White ants can be controlled by applying 5% B.H.C. and 5% DDT @2.5- 5 g/pit at the time of planting.
Red scale:
This is very serious pest of roses which attacks mostly in August and September. The branches are covered with a reddish-brown incrustation under which the insect sucks the juice of the plants. The plants may dry up under severe attack. This pest can be controlled by spraying malathion or parathion or 0.25% Sevin in April and again in October or by the application of Thimet granules in the ground.
Aphids:
These appear in winter months on leaves and flower buds. They suck the cell sap, dis-colour the leaves and affect flower buds which fail to open. This can be effectively controlled by spraying 0.1% malathion or by applying granules of Thimet.
Digger Wasp:
This insect has been found damaging freshly pruned rose plants. They dig burrows into the pith through the cut ends and nest there. Later on fungal attack may be there and stems may dry up. These can be effectively controlled by applying 1% BHC or DDT in fungicide at the cut end at the time of pruning.
Chafer Beetles:
The adults of these beetles appear in August-September and cut away the leaves. This can be controlled by dusting 5% BHC or Aldrin.
Diseases found in Roses:
Die-back (Diplodia roseum):
This is very serious disease of roses and appears after pruning. The drying up and blackening of pruned shoots start from the downwards. If it is not properly controlled it may spread on large scale. For its effective control, the pruned cut end should be painted with a fungicidal paint, prepared of 4 parts copper carbonate, 4 parts of red lead and 5 parts of linseed oil.
Black spot (Diplocarpon rosae):
This disease appears in November and continues till the end of March. Conspicuous circular black spots (less than 1 cm) with fringed margins appear on either side of leaf. Leaves become chlorotic, dry up and prematurely drop. It can be easily controlled by spraying 0.2% Captan or Ferbam fungicides at fortnightly intervals.
Powdery mildew (Sphaerotheca pannosa var. rosae):
It is a serious disease in warm, humid and cool weather conditions. Young growing shoots and leaves are covered with white powdery growth. Infected leaves turn purplish and drop. Flower buds may fail to open. It can be checked by dusting 80% sulphur or spraying 0.1% Kerathane fungicide.