COMMON PESTS AND DISEASES IN AVOCADO
• It is good to note that avocado orchards enjoy natural enemies (predators and parasites) that are able to maintain a biological balance.
• Cultural control is also effective depending on the level of infestation.
• When both the cultural and the biological control system are not working, selective use of chemical insecticides to control pests and diseases is necessary.
• This approach is referred to as IPM.
a) MOSQUITO BUGS (Helopeltis schountedeni) – stainers
a. THE ADULT MOSQUITO BUG:
• Feeds early in the morning hours, late afternoon and at night. They fly quite fast and thus have a potential to affect many fruits.
b. THE NYMPH MOSQUITO BUG:
• They don’t fly and they only affect few fruits that are within their reach.
NB: THIS IS THE BEST STAGE TO CONTROL.
• To make decision on control method, we monitor for the two stages of the pest and for fruit damage.
b) FRUIT FLIES
• The female lays its eggs under the rind of an avocado fruit.
• Careful monitoring using pheromone traps is critical to establish population levels when to control and the efficacy of control measures taken.
• Both natural and chemical methods are used.
• For chemical control, we bait. We use a protein bait as an attractant mixed with a chemical as the poison. Spays are to continue until the trapped number reach 0 and sprayed at low volumes.
• For cultural control method, the key thing is sanitation. Fruits fallen to the ground are also collected and disposed. Routine eradication of alternative hosts like guavas is also done.
c) FALSE CODLING MOTH (FCM)
• It is a major phytosanitary threat.
• When eggs laid on the surface of the fruit hatch, the caterpilars bore into the fruit, rendering it undesirable for consumption and leaving the fruit vulnerable to plant diseases and rot.
• Fruits may also ripen and drop from the trees prematurely. The resulting fruit loss and damage could potentially result in millions in economic losses. The fruit is prone to secondary infections.
d) SYSTATES WEEVILS
• Adult and systate weevil damage.
• Notched (uneven) feeding on the leaves is a classic sign of feeding by adults.
• This is significant on young trees and not big trees.
• The pest hide in the leaves, mulch and soil.
• Control is difficult because of their behavior. Cultural method of control is practiced. If pressure persist, chemical control is done.
• The timing of spray is critical.
• When you see diseases on the tree the damage is done
• Early detection is a great plus.
• Anthracnose & collectrotrichum
• On hass the symptoms will be seen as a bronzing, similar to mite damage on other crops, but has a small lesion and is described as “pepper spot”
• These diseases are most likely to occur during the wet conditions.
• When the fruit is small, i.e. smaller than pegion egg size, it is not susceptible.
• Fruits bigger than this size is susceptible to infection at any time under favorable climatic conditions for the fungus.
• Control with copper.
ROOT ROT MANAGEMENT.
i. Soil Selection
Well drained and aerated.
ii. Resistant/Tolerant Rootstocks
‘Dusa’, ‘Duke 7’, ‘Bounty’
Disease free nursery trees.
iii. Irrigation Management
Beware of over-irrigation in sick trees
Use of micro-jet or drip irrigation for better control.
iv. Chemical Control
Young trees use Alliete paint.
Mature trees inject with Phosphorous acid.
For more information on hass avocado management contact us or visit our offices at Hermes House Nairobi Tom Mboya street opp K.T.D.A