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KMS Kenya  (18-03-2013)  Anthony Biegon

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Grey patches on apple stem

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Apple fruit trees declining in terms of production due to poor health

This is a physiological condition which is caused by aging that leads to cover of apple branches and stem by lichens. Lichens grow on the surface of barks and do not have an effect on the tree. In rare situations, lichens can grow to form very thick layer

 

03 Name of the expert:

Dr. Lusike Wasilwa

04 Email address of expert:

lwasilwa@gmail.com

06 Profession of Expert:

Molecular Plant Pathologist/ Plant Breeder

07 Organisation of expert:

Kenya Agricultural Research Institute

08 Practical experience:

Over 20 years

09 Diagnosis:

This is a physiological condition which is caused by aging that leads to cover of apple branches by lichens. Lichens grow on the surface of barks and do not have an effect on the tree. A lichen is not a single organism the way most other living things are, but rather it is a combination of two organisms which live together intimately. Most of the lichen is composed of fungal filaments. They make their own food and just use the tree for support. In rare situations, lichens can grow to form very thick layers shading the tree resulting in defoliation. Lichens are formed by green algae and fungal tissue. Moreover lichens are beneficial to the environment and function by regulating the composition of gases

10 Practical Instruction:

- Orchard management - Ensure that field receives sufficient sunshine and soil is well drained. Lichens thrive in locations that are moist, cool and receive insufficient sunshine. Keep the field clean of weeds to enable air movement. Remove surrounding bushes for more air movement.
- Tree management. Prune and thin-out branches using the central-leader system to allow better penetration of light and air-flow.
- Age - Confirm age of apple trees and level of production. If the trees are too old, then consider uprooting them and starting a new orchard.
- Control – You can annually remove lichens by gently (ensuring that you do no injure the bark thus predisposing it to diseases) scrubbing the bark with a solution of liquid soap. Or can spray lichens with ½ cup of baking soda mixed in 1 gallon (3.4 litres) of water.
- Chemical control – Can spray trees with copper-sulfate or lime sulfur following manufacturers’ recommendations during the dry season on only branches with lichens

If production of these trees is low, they have to be pruned back and top-worked with current recommended varieties. Top working involves grafting new plant varieties onto older plant varieties which are already established in the field

11 Conditions for success:

Follow the above practical instruction and manufacturer’s recommendations on use of fungicides

12 Conditions for failure:

- Poor field site receiving low sunlight that is poorly drained and thus tend to be moist and cool
- Use of wrong fungicides or those that are dilute because of not following the manufacturers recommendations

13 Expected short term effect:

No new lichens on branches observed

14 Expected mid-term effect:

Plants rejuvenated and new growth is observed

15 Expected long-term effect:

Healthy barks and vigorous plants

16 How common is the problem:

very common

17 Importance:

of minor importance

18 Since when is it known:

more than 20 years

19 Tendency:

unvarying

20 Geographic extent:

in some parts of the country

01 ID of the request in RUN:

8145

this is the answer to id: 8145
 
Classification
 
Africa Kenya Journal:KMS Kenya
 
Section:
  • Protection and Health
  •   Products:
  • Apple
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    Author´s email:
     Email des Autors abiegon@kari.org
     
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  • Photo of a top-worked mature apple plant
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    Related links..
      Top working on apples     Definition and description of lichens     How to kill lichens on apple trees