Insect pests
- White ants
They attack the plants and damage the root system and slowly plants die completely. White ants can be controlled by applying 5% sevin @ 2.5-5 g/pit at the time of planting.
- Red scale
The branches are covered with a reddish-brown encrustation under which the insect sucks the juice of the plants. 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 in the ground.
- Aphids
These appear in winter months on leaves and flower buds. This can be controlled by spraying 0.1% malathion or by applying granules of thimet.
- Digger wasp
They Damage freshly pruned rose plants and are controlled by applying 1% sevin in fungicide at the cut end at the time of pruning.
Diseases
- Die-back (Diplodia roseum)
This appears after pruning. The drying up and blackening of pruned shoots start from the downwards. 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 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.
Source: http://www.indiaagronet.com/indiaagronet/floriculture/Floriculture.htm