SCIENTIFIC NAME: Annona species
FAMILY: Annonaceae

In September, 1981, the atemoyas (Annona cherimola x A. squamosa Hybrids) African Pride and Pink's Mammoth were pruned and defoliated to observe effects. The plants flowered immediately on bud burst and this was all that was noted.

In April 1984, the above was carried out again in a range of Annona sp. (A. atemoya, A. reticulata, A. cherimola, A. muricata, Rollinia deliciosa, R. mucosa) and the growth hormone Gibberellic Acid (G.A.3) was applied to the flowers to observe the effect on fruit set.

A moderate to heavy pruning was carried out followed by an Ethrel® spray at 50 P.P.M. on half the pruned trees of each species. There was little difference between the Ethrel-treated and untreated trees, especially the A. cherimola and A. atemoya where the pruning removed virtually all leaves. Bud burst and flowering occurred immediately on the A. atemoya and A. cherimola; the Rollinia species followed with A. muricata being vegetative and A. reticulata last but with flowers.

G.A.3 sprays commenced weekly at 50 P.P.M. African Pride was the only tree to respond to this concentration for the first 3 weeks, so the rate was increased to 100 P.P.M. The Pink's Mammoth and Cherimola set at this rate under adverse weather conditions. None of the other species responded.

It was concluded that pruning and G.A.3 sprays at 100 P.P.M. weekly can be used to produce fruit out of season in A. atemoya and A. cherimola on varieties African Pride, Pink's Mammoth and Mossman respectively.

Wayne Hancock, Darwin

DATE: November 1984

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