This is a follow up article to that which appeared in the Rare Fruit Council of Australia July, 1992 Newsletter No. 75, 4/92.
Following that article I was fortunate to talk to Mr Jude Lai, of Beenleigh, South East Queensland and Mr Col Gray who has a Durian orchard at Cape Tribulation, Far North Queensland.
Jude is growing quite a few Mamey Sapote and several Green Sapote trees. He said that he felt that the problem of the cracking and splitting of the bark was not because the Green Sapote scions were incompatible with the Mamey Sapote rootstock.
He was of this opinion because some of his grafted Mamey Sapotes (Pontin and Magana) had splitting and cracking of the bark. This was worse in areas of poorer drainage. Jude was convinced that this problem is the result of Phytophthora attacking the roots and as they become more inefficient the bark begins to shrink which causes the cracking.
Several months after speaking with Jude I visited Col and Dawn Gray at Cape Tribulation, North Queensland. Col showed me the troubles he was having with his Durians following the severe buffeting and flooding caused by tropical cyclone Joy the previous year.
A large number of trees had died. Some were near skeletons, showing severe cracking and splitting of the bark while the majority seemed to be recovering.
Col was sure these problems were the result of Phytophthora palmivora entering the trees' system as they were being blown and buffeted by the cyclonic winds.
This apparently is quite a common problem in Malaysia. The treatment in South East Asia is ground applications of Ridomil.
Col treated his trees with both Ridomil and Phosphorous Acid. The Phosphorous Acid was both foliar-applied and injected into the trunk.
In my case, I applied one application of Ridomil 50g at the rate of 100gms per sqm to the ground under the tree canopy. This was done in September 1992 and since that time the tree has flowered and set 19 fruit, of which 15 have stayed on and are nearly ready for picking.
The tree is now quite vigorous, in excess of 3m in height and producing a very large quantity of flowers.
The Phytophthora treatment has given the tree a new lease of life, and for this I must thank my fellow Rare Fruit Council members.
DATE: September 1993
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