Wednesday, February 25, 2015

Ipomoea triloba

Ipomoea triloba is a species of Ipomoea morning glory known by several common names, including littlebell and Aiea morning glory. It is native to the tropical Americas, but it is widespread in warm areas of the world, where it is an introduced species and often a noxious weed. This is a fast-growing, vining, annual herb producing long, thin stems with ivy-like, petioled, heart-shaped leaves 3 to 6 centimeters long. The leaves sometimes, but not always, have three lobes. The vines produce tubular bell-shaped flowers, each about two centimeters long. They are quite variable in color, in shades of pink, red or lavender, with or without white markings.
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I. triloba is considered a serious weed in Australia and the Philippines; a principal weed in Cuba, Hawaii, and Honduras; and a common weed in Argentina, Jamaica, and Indonesia (Holm et al., 1979). Like other 'morning-glories', it competes with crop plants for nutrients and water. Due to its twining nature, it also fouls mechanical harvesters. It has been noted as one of three morning-glory weeds of cotton fields in Arizona, USA (G Yatskievych, University of Arizona, personal communication, 1981). 

In Java, I. triloba is a weed of brushwoods, living fences, sugarcane fields, roadsides, fields and waste places (van Ooststroom, 1965). A nematode assessment survey of the vegetable-growing areas of Barangay Sicsican in Talavera, Neuva, Ecija, Philippines found that I. triloba and several other weeds serve as alternative hosts for root-knot nematodes (Meloidogyne javanica and M. incognita). Such alternative hosts play an important role in the nematodes' ability to survive and persist during the rice season before the vegetable season (Mamari and Alberto, 1989).

In the Philippines, I. triloba is one of the main weeds of monoculture maize (Pamplona, 1988), one of the most common weeds in intercropped maize, sorghum, sunflowers, coconuts, tomatoes, and sesame (Moody, 1986), and has been listed there as one of 21 common weeds of cotton (Paller and Lijauco, 1981). 

In one study, varying densities of I. triloba were maintained in monocultures of soyabeans or maize and maize-soyabean intercrops. Weed density did not normally have a significant effect on insect pest populations, but the presence of I. triloba tended to increase damage by insects in soyabeans and to act as a pest attractant in maize (Mercado et al., 1980).

I. triloba was first reported in Israel in 1986 as a weed in cotton (Joel and Liston, 1986).

Studies in the Solomon Islands showed that I. triloba and two other species are alternative hosts for witches' broom disease of sweet potatoes (Jackson and Zettler, 1983).

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