Friday, July 27, 2012

Insect pests of Gmelina arborea (Kumil in Tamil)

Dear Friends,

We all accept the adage that 'A picture is worth more than a thousand words'. This preamble is necessary since this post bear more photos and a few words. 

As in my earlier post, here also I heavily relied on the photographs and subject content of Dr.Balu, Scientist, Forest Protection Division, IFGTB, Coimbatore on 'Insect pests of Gmelina arborea' (Kumil in Tamil).

Insect pests are broadly classified as:
  • Defoliators  
  • Leaf miners  
  • Sapsuckers
  • Gall makers
  • Root feeders
  • Shoot borers
  • Bark feeders   

In general, Gmelina arborea (Kumil) is susceptible to pest attack, hence  farmers avoid planting them as inter crop inside orchards. One of the main causes of Gmelina arborea's poor bole form attributes to this high incidence of pest attack. 
Some of the insects that cause damage to Gmelina arborea (Kumil) plantation are discussed here under:
Leaf Miners:
Leaf miner is larva of an insect that lives in and eats the leaf tissue of plants. For more info: Click.  
Sap Suckers:
Organisms involved:
Aphids, Psyllids (Jumping plant lice), Plant bugs, Scales, Mealy bugs, leaf hoppers, thrips, Whitefly and mites.
Damage caused:
curling and bunching,
yellowing and withering of leaves,
wilting and drying of entire seedlings.
Inject toxic salivary secretions and responsible for spread of viral, fungal, mycoplasmal and bacterial diseases. 
In farmer's meetings (and nowadays in many Agri portals also) most of the Gmelina (Kumil) growers used to lament that growing tip (Young shoot) of young Gmelina plants got dried up resulting in growth retardation and branching.

Root cause of this attack is usually by the Tingid bug shown in the picture below. It sucks the sap from the leaves and young shoots resulting in curling, drying and withering of not only leaves but also tender shoot tips. Farmer  may incur severe economic loss if this bug attack is not managed well properly.   
Organisms involved:
            Caterpillars, Bagworms, Beetles and Weevils,
            Grass hoppers and Slugs.
Damage caused:
            Feed on growing points of plants,
            Feed on entire leaves, 
            Feed on surface tissue,
            Notch the edge of leaves,
            Leaves riddled with smaller to larger irregular holes, 
            Roll up and web the leaves and feed. 
            Browse the bark,
            Cut the stem.

Wing/Wingless Grosshoppers:

         Shoot borer
         Bark feeding borer/feeder
         Stem borer
         Stem and root borer

Goats likes to eat the bark of Gmelina, resulting in permanent injury to the stem. In the picture published here, the damage is caused by Bear. One of the effective ways to ward off animals in the unfenced farm land is by applying fresh cow dung + cow urine mixture on the stem upto a height of 5 feet.  

On field trials in my farm, I found out that Entomopathogenic fungi: either
Beauveria bassiana or Metarhyzium anisopliae in association with Verticillium lecanii  were pathogenic to all pests of Gmelina. Beauveria bassiana was found to be more effective than Metarhizium anisopliae. 

Click on the names to learn more about these bio-control agents.

Trials were conducted in my Acid Lime orchards and Moringa orchards (Drumstick tree) also. A minimum of two to three sprays is necessary for complete control of pests. Subsequently, the number of spray applications (No. of cycles) per season will come down and you will be surprised to observe that there is increase in time between spray cycles also.  

To know about Mechanical, Cultural, Behavioural, Botanical, Biological and 

Chemical control of all the above Sucking pests and leaf eating caterpillars 

please visit: Ppt presentation on Integrated Pest Management (IPM) by 

(the same author) Dr.Balu, a renowned Entomologist. The above Ppt

presentation is also uploaded in top right side of this blog which can be 

used as a ready reckoner by our readers for the control of Insects and 

diseases in almost all the crops. 


A.Vishnu Sankar.

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