I) Management of Groundnut bud Necrosis:-

    This is a virus disease causing more damage to groundnut crop during kharif and summer. Virus is mainly transmitted through thrips (Thrips palmae).

 

Symptoms:

    Disease first appear on young lenflets as chloratic spots or mottling that may develop into chloratic and Necroptic rings and streaks. Terminal bud Necrosis occurs when temperature is relatively high. As plant matures, it becomes stunted with short internodes and proliferation of Axilary shoots.

 

II) Management/Control measures:-

III) Control of Tobacco caterpiller in soyabean:-

SYMPTOMS:

    Spodoptera is a polyphagous pest farmed damaging throughout the country. Peak incidence would be in August-September. Freshly hatched larvae feed gregareously, scrapping the chlorophyl. Soon dipose later stages feed voraciously on the foliage at height, hiding usually in soil around the base of the plants during day time. Sometimes the Feeding is so heavy that only petioles and breaches are left behind.

Management/ Control measures:-

  1. Use pheramone traps 2-3 per acre to monitor the post.
  2. Spray the crop with neem seed Keanee extract 5% or vitex nigundo 5% at 40 days after sowing.
  3. Spray S1 NPR at 250 LE per hectare at 35 days after sowing .
  4. Sow castor as trap crop on the margin of the land, collect egg masses and early larvae and destroy.
  5. Spray Chloro keyriphos at 2ml/liter.
  6. Growing larvae could be controlled by using poison bait. (Monocrotophous or curbaryl  10 ml+  Rice bran 1 kg+  Jaggary 100 gm and water 100 ml to moister bait).

 

1.0 BACKGROUND

A virus disease caused nearly Rupees 300 crores worth of crop losses to groundnut in Andhra Pradesh during kharif in the tar 2000. It was presumed to be caused by peanut bud necrosis virus (PBNV), a virus known to be widely distributed in India. Research done recently has shown conclusively that the disease if found to be caused by a totally nee virus. As a result the disease is named '' Peanut Stem Necrosis'' (PSND) and is caused by an isolate of tobacco streak virus (TVS).

 

In some respects peanut bud necrosis disease (PBND) and PSND resemble. However there are many distinguishing features and are listed under table I. Therefore the main objective of this course is to acquaint the participants with the distinguishing features of PSND and PBND.

2.0 CHARACTERISTICS OF PSND

2.1 Symptoms on groundnut:

Initial symptoms as large necrosis lesions on young quadrifoliates. These coalesce and cover the entire leaflet, leading to complete necrosis of young quadrifoliates. This symptoms will be followed by necrosis of the entire stem located below the necrosed quadrifoliates. If young plants are affected ( less than one month old), the entire plant is often necrosed. In the case of older plants one or more branches will show necrosis. These plants are stunted and often do not show axillary shoot proliferation as in the case of PBND. Only apical branches showed some axillary shoot proliferation.

Necrotic spots are observed on the majority of pods. Size of the pods is severely reduced and kernels are not marketable. Tests conducted on TMV-2 cultivar until now indicate that the virus is not seed-transmitted. However, seed-transmission of plant viruses is a complex phenomenon. It depends on when the infection occurred, genotype, as well as environmental factors. Therefore additional tests are necessary to conclude that the virus is not seed transmitted in groundnut.

2.2 Host range of the causal virus tobacco streak virus (TVS)

It has been conclusively shown that PSND is caused by tobacco streak virus (TVS). The virus infects many plants, including the most commonly present weeds in groundnut fields. On the majority of the hosts it produces either necrotic or chlorotic lesions, followed by systemic necrosis.

3.0 CHARACTERISTICS OF PEANUT BUD NECROSIS DISEASE (PBND)

3.1 Symptoms on groundnut

Primary: A wide variation of symptoms is often observed. Initial symptoms appear as faint chlorotic spots and mottling which develop it to chlorotic and necrotic rings and streaks. Petioles bearing fully expanded leaflets with initial symptoms become flaccid and droop. This symptoms is followed by terminal bud necrosis. It is important to realize that terminal bud necrosis is common on crops grown in dry ( summer) and kharif season indication that it occurs when high temperatures prevail. If very young plants are infected, the entire plant will be necrosed, again when high temperatures prevail.

Secondary: Primary symptoms are followed by secondary symptoms. These are stunting and proliferation of axillary shoots. Leaflets formed on the axillary shoots show a wide range of symptoms including reduction in size, distortion of the lamina, mosaic mottling and general chlorosis. These secondary symptoms are most common on early infected plants giving them a stunted and bushy apperance.

The virus also caused severe reduction to yield. Early infected plants do not produce any yield. Late infected plants produce small pods with shirveled see. Seed testa is often mottled or discolored.

4.0 DISTINGUISHING FEATURES OF PSND AND PBND

 

  PSND by TVS PBND by PBNV
A. Symptoms
Groundnut Necrosis lesions on terminal leaflets, complete stem necrosis and often total necrosis of entire plant.

Axillary shoot proliferation, restricted to apical portion may occur

Necrosis spots on pods. Testa are not discolored or mottled.

No evidence of seed transmission . Additional tests necessary.

Chlorotic lesions on terminal leaflets, ring spots and often necrosis of terminal bud. Axillary shoot proliferation with small and deformed leaflets. Infected plant remain stunted and seldom die.

No Necrosis spots on pods and testa are discolored and mottled.

Definitely not seed transmitted.

B. Serological Cross Reaction
  Ilarviurs in Bromoviridae Reacts with many tobacco streak virus antisera. Distinct tospovirus and reacts only with peanut buc necrosis virus antiserum.
C. Seed Transmission
  Seed-transmitted in many hosts Not seed-transmitted in any of the hosts
D. Thirps Transmission  
  Transmission by Thrips Plami in a persistent manner Transmitted by several thirps Relationship is passive
E. Primary Spread
  Mostly weed hosts Weed and crop plants
F. Secondary Spread
  Selected weeds and crop plants Selected weeds and crops plants
G. Management
  Suggested:

- Border cropping,

- Inter cropping,

- Plant population,

- Insecticides not recommended

 

- Date of sowing,

- Plant population,

- Inter cropping,

- Host-plant resistance,

- Insecticides not recommended