Pest Survey of Vernonia galamensis in Ethiopia

INTRODUCTION Recent decades have witnessed an increase in the rate of desertification of agricultural lands. More than one-third of our planet’s land is now arid. Water for crops and an increasing human population is rapidly becoming a critically short commodity. Yet none of the major crop plants of the world is well adapted to arid lands. Efforts have been made to introduce new crops, which are essentially noncompetitive with the existing crops and possibly provide a new and unique product for industrial use particularly for marginal rainfall areas. Vernonia galamensis (Cass.) Less, Asteraceae is a new industrial crop originating in Ethiopia which combines all the possible merits for the semiarid tropics and subtropics (Baye et al. 2000). Vernonia galamensis is limited in distribution and endemic to primary East African countries as a weed colonizing disturbed areas and bare agricultural lands. According to the recent taxonomic revision of the complex, this species has six sub-species (nairobensis, gibbosa, lushotoensis, afromontana, mutomonesis, and galamensis). Sub-species galamensis is the most widely distributed; it is highly diverse with four botanical varieties (galamensis, petitiana, australis, and ethiopica) (Gilbert 1986). Vernonia galamensis ssp. galamensis var. ethiopica is a new annual industrial oilseed. It grows naturally in marginal areas with as little as 200 mm seasonal rainfall and at an elevation ranging from 700–2400 m in the southern and southeastern parts of Ethiopia (Gilbert 1986). It was first identified in eastern Ethiopia by R.E. Perdue Jr. in 1964 at 7 km south east of Harar town (9° 14'N and 42° 35'E at 1700 m). It has unique properties which make it interesting both economically and ecologically (Perdue 1988). The oil (35% to 42% of the seed), contains an important epoxy acid called vernolic acid (72% to 80% of the oil). Vernolic (cis-12, 13-epoxycis-9-octadecenoic) acid, a naturally occurring epoxidized fatty acid, is primarily present in the oil as the triglyceride trivernolin with unique physical properties in particular low viscosity. Vernolic acid, beside other uses, is a useful raw material for manufacturing paints and coatings. Vernonia oil also contains linoleic acid (12% to 14%), oleic acid (4% to 6%), stearic acid (2% to 3%), palmitic acid (2% to 3%) and a trace amount of arachidic acid (Thompson et al. 1994). Agronomic data shows that the plant requires a welldrained soil and restricted naturally to grow in the region 20° north and south of the equator. Very recently, the plant was found to be a potential crop for inclusion into the agricultural system in Ethiopia. Among other characters, a seed yield up to 4000 kg/ha and an oil content of 40% using unimproved local materials was obtained which is much higher than found elsewhere (Baye 1996, 1998, 2000; Baye et al. 2001). On the other hand, there is no information on the pests and diseases of Vernonia. Thus, this preliminary survey was conducted to see the associated pests and diseases of V. galamensis spp. galamensis var. ethiopica and design a breeding strategy in a multidisciplinary approach which will help to foster its improvement as a potential new industrial oilseed crop for Ethiopia.