Effect of fertilization on the abundance of Heteropsylla cubana Crawford on Leucaena leucocephala (Lam) de Wit [Philippines]
1988
San Valentin, H.O.
This study evaluated the effects of fertilization on potted ipil-ipil on two types of soil and on the number of psyllis. The growth of ipil-ipil was stunted in Luisiana clay even upon application of lime and different fertilizer treatments. Plants grown in Lipa clay loam significantly increased in height and shoot length upon addition of N with or without P and K. Increasing the rate of N with P and K from 15 kg/ha to 30 kg/ha with or without P and K resulted in significantly different height. The presence of P at zero N resulted in significantly different shoot length over those that received zero P. The tallest height and longest shoot were observed in plants that received 15-0-0 treatment. The data show that the psyllid number was consistently more abundant in plants grown in Lipa soil. In both types the number of adults was similar for all treatments. The effect of treatments on the number of eggs and nymphs on 4 months old seedlings in Lipa soil was significant at 1% level. The number of eggs increased significantly at 15, 30 and 60 kg N/ha over zero N with or without P and K. The number of nymphs increased when N was applied regardless of P and K levels. The study shows that the plant's response to fertilization depends on the native chemical properties of the soil at the time of imposition. Enhancement of growth through fertilization offers a variety of host conditions for the insect to colonize. Increased space offered by enhanced growth attracted more psyllid numbers. The results suggest that fertilization of ipil-ipil as a cultural practice to improve outplanted seeding survival could increase the plant's predisposition to psyllid attack.
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