Page 26 - FRUTAS DEL TRÓPICO

26 Frutas del trópico

The next step in a mango flowering management program is to decide whether to
use paclobutrazol or not. The triazole plant growth retardants, paclobutrazol (Cultar, Ze-

neca Corp.) and uniconazole (Sumitomo or Valent Corp.), are inhibitors of gibberellin

biosynthesis (Rademacher, 1991); therefore, they reduce the levels of the putative vegeta-

tive promoter, thought to be a gibberellin. Both products are effective for assisting in floral

induction with uniconazole being about 10 times more effective than paclobutrazol. Both

products are expensive, and they can cause permanent stunting of flushes if trees are seve-

rely pruned at any time after soil application (Davenport, 1994). These chemicals provide

a strong measure of certainty that flowering will occur, when used properly, by shortening

the time required between the synchronizing pruning and application of floral-stimulating
nitrate sprays (Table 1) (Nartvaranant et al., 2000; Tongumpai et al., 1991; Voon et al.,

1991). The triazole products provide the flexibility needed to shift the flowering time of

the more-difficult-to-manage cultivars like ‘Tommy Atkins’ to any week of the year with less

concern for early vegetative flushes. For this reason, paclobutrazol has been widely marke-

ted throughout the tropics to stimulate mango flowering.

Either product should be applied after the onset of re-growth following pruning (1 to 1.5

months after prune date) depending upon cultivar. Paclobutrazol should be applied in a soil
drench containing 1 to 1.5 grams of active ingredient per meter of canopy diameter (Nartva-

ranant et al., 2000) if applied during the rainy season, but personal experience has shown that

about half that amount is needed if applied during the dry season. It takes at least 90 days for

either product to exert an effect in trees (Nartvaranant et al., 2000). Earlier initiation of flushes

results in formation of vegetative shoots so it is still important to avoid growing conditions that

promote initiation of frequent flushes when utilizing paclobutrazol.

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