Wilt

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What is wilt?

It is the most vicious disease in guava orchards. In VNR-BIHI plants, this disease can be seen as secondary infection after nematode infestation or injury to roots.

The exact cause of the disease is still not fully understood but the pathogens, viz. Fusarium oxysporum f.sp. psidii, F. solani, Macrophomina phaeseoli, Rhizoctonia bataticola, Cephalosporium sp. and Gliocladium roseum are reported to cause wilting.

 

 

 

 

 

 

 

Symptoms

  • First external symptom of the disease is the appearance of yellow colouration with slight curling of the leaves of the terminal branches. Plants, at a later stage, show yellow to reddish discoloration of leaves.

  • Subsequently, there is premature shedding of leaves. Some of the twigs become bare and fail to bring forth new leaves or flowers and eventually dry up.

  • Fruits of all the affected branches remain underdeveloped, hard and stony. Later, the entire plant is defoliated and eventually dies.

  • The roots also show rotting at the basal region and the bark is easily detachable from the cortex. Light brown discoloration is also noticed in vascular tissues.

  • The pathogen attacks young as well as old fruit bearing trees but older trees are more prone to the disease.

 

 

 

 

 

 

 

Mode of spread:

  • Through movement of plants containing sick soil in virgin areas.
  • Short distance spread is by water.
  • Root injury or nematode infestation.

Reasons of severity:

  • Making raised beds after plantation and burying graft union.
  • Stagnation of water in guava field for long duration.
  • Maximum and minimum temperature ranges 23-32C with 76% RH are conducive.
  • Lack of timely application of suitable control measures.

Management:

  • Disease can be kept under check by proper sanitation in the orchard. Wilted trees should be uprooted, burnt and trench should be dug around the tree trunk.

 

 

 

 

 

 

 

  • While transplanting, roots of plants should not be damaged severely.

  • Maintenance of proper tree vigour by timely and adequately pruning.

  • Initial symptoms can be controlled by drenching the soil with Ridomil gold + copperoxychloride @2gms. each per liter water

  • Eco-friendly approach of guava wilt control is suggested where biological control, soil amendment and intercropping are effective.

  • Prevent nematodes.