MANAGEMENT OF TOMATO FUSARIUM WILT BY MANIPULATION OF ENVIRONMENTAL CONDITION

ABSTRACT

The study was aimed at investigating the effect of manipulating growth environment in controlling Fusarium wilt pathogen in tomato. The research was in two phases. The first phase involved an in vitro experiment, where potato dextrose agar used to grow Fusarium oxysporum was supplemented with nitrogen, phosphorus and potassium; singly and in combination (NP, NK, NPK and PK). Another experiment involved varying the pH (3, 5, 7, 9 and 11) of the growth medium used to grow the pathogen. The second phase of the research was an in vivo experiment where Fusarium spore suspension was prepared and used to infect tomato seedings at 4-leaf stage. These were planted in soils with varying amount of nitrogen (50, 100, 150 and 200 mg urea was used as source of nitrogen/ kg soil sample). Plant height and symptom scores were recorded at 5 and 10 days post inoculation (dpi). The results obtained indicated that the presence of Nitrogen alone inhibited the growth of the fungus, while other nutrient combinations supported growth of Fusarium oxysporum. The different concentrations of pH used promoted growth of the fungus, except in pH3 where improper gelling of the medium as a result of its high acidity was observed. The results of the in vivo experiment showed that there was low symptom expression in the tomato seedlings grown on soil amended with 100 mg urea/ kg soil sample with plant heights of 19 cm and 21 cm at 5 and 10 dpi, respectively. The findings from this study suggest that amending soil with urea can be used to manage Fusarium wilt disease in tomato.