Chilli Capsicum annuum L. is the most widely cultivated species all over the world for its pungent fruits. Chilli is cultivated for both green and red and also called as hot pepper. Chilli crop belongs to solanaceous family and is vulnerable to some of the diseases which are caused by infectious bacteria, fungi and deadly viruses. Important diseases are discussed with their management startegies.
1. Damping off
Damping off disease is caused by infections and as well as more moisture and less moisture. More moisture also supports fungal and other pathogen. Both pre-emergent and post emergent symptoms are common. Seedlings are killed at nursery and transplanted seedlings will also be killed. Infected tissues at the stem base and root base will be water soaked and soft later turning black killing the young plants.
2. Leaf spot:
Fungal spots and bacterial spots are commonly found on chilli crop. Bacterial spots are characterized by the yellow ring around the ring but fungal spots are not. Septoria, cercospora leaf spots are more common.
Chemical control of Cercospora and Alternaria leaf spot control
3. Stem rot
Stem rot is characterized by water soaked light browner coloured patches on any part of the plant branches, they decay and all the leaves drop off with wilting symptoms.
The control measure for leaf spot diseases can be used to control the stem ro tin Chilli.
Anthracnose disease is more prominent in high moisture with cooler temperatures. The leaves will show the symptoms of black spot and on fruits the spots will be surrounded by the reddening. The disease will also show symptoms after at post-harvest stage.
5. Powdery mildew
Yellow blotches on upper surface of the leaves with Powdery-white fungal growth on the undersides of leaves are observed. The infected leaves curl upward. Usually the older leaves are infected first later move on to younger leaves. Infected leaves drop from the plant prematurely and many times the fruits are exposed to sunlight making the fruits sunscald.
6. Viral infections
Viral infections in chilli crops is another major diseases which cause much crop losses. Some of viral infection symptoms are mosaic, yellow mosaic, mosaic mottle, leaf curl, leaf roll, bushy stunt and leaf necrosis.
These viral infections’ symptoms are combinedly called as muruda. White flies transmit the virus from plant to plant.
6.1 Leaf curl virus or Gemini virus
Leaves are malformed and curled inwards to the side of mid rib with stunted plant growth. Flower parts under develop without forming to fruits.
6.2 Mosaic Viruses:
Irregular light green and dark patches with mosaic appearances are observed on the leaves with smaller size. Stunted growth with yellow chlorotic ring spots on the under developed fruits.
6.3 Tomato Spotted wilt virus
Recently the Tomato Spotted Wilt virus [TOSPOW] is common viral infection in tomato and the disease has also shown symptoms in chilli and capsicum. The leaves turn yellow, elongates and cluster apical growth is observed with little or no fruit set. The crop grown in high temperature season, with high use of ammoniacal nitrogen as nitrogen nutrient sources.
Viral diseases are spread from plant to plant at young growing stages before the age of 25 days and this particular stage is most vulnerable stage for spreading and carrying the viral infections which may express at later stages.
So, raise the saplings under controlled conditions where the germinated saplings or seedlings will be protected from sucking pest vectors like whiteflies, thrips, aphids and other plant hoppers providing minimal chances of viral infections at later stages.
In the main field the management of the viral infections the vector management is foremost. In addition to the management of sucking pests like whiteflies, aphids and thrips the supplement of plant stimulants may help plants develop some kind of inhibition towards virus attack and also bind the active viruses in the plant sap, so that the multiplication and further damage may be reduced.
Following combinations may be sprayed to manage both sucking pests [Vectors] as well as bind or develop resistance of plants against viral infections in the plants. 7 days intervals is required in between the sprays.
1. Use of more and more nitrogen to the chilli crop leads to the susceptibility o chilli plants to the viral infections especially ammoniacal nitrogen present in the fertilisers and other inputs which are supplemented to the crops will increase the viral infections. Amides formed in the plant sap from ammoniacal nitrogen sources will help the virus to multiply at higher rates increasing the symptoms.
2. Avoid Poultry manure, because poultry manure contains large quantities of ammoniacal nitrogen which Poultry manure need to be decomposed for minimum 6 months and be mixed 50: 50 red soil and poultry manure respectively before application.
3. Urea and Ammonium Sulphate contains ammoniacal nitrogen, better to limit of avoid using these fertilisers
4. Amino acids supplements through sprays and soil drenchings may be avoided to suppress the viral multiplications in the plant system.
5. Supplementation of Manganese micronutrients through foliar sprays and soil application will help in managing the viral infections not only in chilli but also in vegetable crops.
K SANJEEVA REDDY,
Senior Agronomist, BigHaat.
For more information kindly call on 8050797979 or give missed call on 180030002434 during office hours 10 AM to 5 PM
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