SHADE-BASED CONTROL OF IMPERATA-CYLINDRICA - TREE FALLOWS AND COVER CROPS

Imperata is shade-intolerant, although little is known of the relative roles of competition for light, water and nutrients in suppressing it s growth. Shading of Imperata results in reduced carbohydrate storage, reduced rhizome and tuber-bulb production, reduced shoot dry weight, increased susceptibility to competition, increased susceptibility to h erbicides and decreased vigor/regeneration. Herbaceous cover crops in the genera Calapogonium, Crotoleria, Mucuna and Pueraria have been sho wn to effectively suppress Imperata growth and can be used to prevent and in some cases eradicate Imperata. Tree fallows with fast-growing s pecies such as Sesbania sesban, Acacia nilotica and Leucaena leucoceph ala can improve soil physical and chemical properties and suppress wee d growth. Forest plantations have been successfully used, particularly with the use of moderate to high tillage, weeding and fertilizer inpu ts to suppress Imperata growth. These plantations produce marketable w ood and reclaim the site for other uses. Additional research is needed to evaluate the specific nature of competition and allelopathic effec ts from Imperata. Continued evaluation of tree species and provenances for Imperata suppression, forms of tillage after woody fallow crops a nd the constraints to adoption of cover crops and trees as Imperata co ntrol measures are also needed.