EFFECTS OF FERTILISER ON THE SUSCEPTIBILITY OF DURIAN AND PAPAYA TO PHYTOPHTHORA PALMIVORA

A complete liquid inorganic fertiliser (Vitall^TM) and organic composted chicken manure were compared in pot trials for their effects on the growth of papaya, and on the susceptibility of papaya and durian to disease caused by Phytophthora palmivora. A single application of 2.5% chicken manure, or regular applications of Vitall led to increased growth in papaya seedlings over a 3-month period, compared to seedlings grown in unfertilised vermiculite/sand (50:50). Regular applications of half the recommended rate of Vitall produced the largest seedlings. Root dry weights were greater in fertilised than in unfertilised treatments, but did not differ between the inorganic and organic fertilisers. In contrast to the Vitall treatments, the incorporation of chicken manure into the potting mix led to increased survival of P. palmivora-infected papaya and durian seedlings, stimulated root regeneration in papaya after infection with P. palmivora, and the reduction of P. palmivora in the potting mix to undetectable levels within 4 weeks. The improved survival of infected papaya and durian grown in chicken manure amended potting mix was attributed to the higher levels of antagonistic microorganisms, such as actinomycetes, which led to the suppression of the pathogen.