ABSTRACT

 Investigations were conducted to characterize and identify of the bacterium responsible spot trials were conducted to assess the effect of sowing dates on disease incidence and severity of the disease on tomato Lvcopersicum escideniurn. Mill. Results of cultura puysicai ailu oiociiemieai stuuies snoweu mat tie pauiogeii isoiateu iroiji oacienai spot lesions on tomato was a Gram-negative, yellow aerobic and rod-shaped bacterium with polar flagellum. The bacterium exhibited strong starch hydrolysis, metabolized glucose I __l _ . _1 ' ---------l• -------------I I ._ 1'_ I I__1 -. anu prouuceu aciu iroill araumose, sucrose, aiiu ceiloulose OUt 1101 110111 uuieitoi 01 sorbitol, also nitrate was not reduced to nitrite. The pathogen was found to be temperature specific and pathogenic on tomato. Based on these characteristics, the bacterium was -- ,,. ------------------------------- Ir.lsrs CI -i'll iuenuiieu as Aw'IInoriwnus uurnpcsiris pv. ves,cworiu LI01UC) IJye. eeus 01 an men cuitivars of tomato tested were susceptible to infection by the pathogen, which was found to be seed- borne. Tomato seeds were also found to be the source of primary inoculurn in - --- --- 1- /..J T------ - _ I. /i -- ------ -- I tfle nelu. raiiy sown seeus 11i1U JUIIC) sigiiiiicaiiuy r U.U) ieuueeu ulsease seeiity (2.25 and 2.58 in 2002 and 2003 respectively) and enhanced fruit yield (11.11 and lO.44tlha in 2002 and 2003 respectively). Late so seeds (late July). were associated with high disease severity (16 and 5.33 in 2002 and 2003, respectively) and lower crop yield of 0.27 and 2.14V1ia in 2002 and 2003, respectively). Early planting in the first or second week of June enabled tomato crop to escape disease since the critical period for 1' -r I ml - .1 l_ - .-- - ___l --------- tue iniecuon was lU iuiy. inc iweive piant exiracts evatuateu ior uaeieneivai eliects resulted in significant (P 0.05) reduction in disease when compared with the untreated controls. Azadirachta indica and Piper nigrum seeds Citrus sinensis peel cold water xiv A extracts significantly (P 0.05) inhibited bacterium growth by 40.35%, 33.0% and 34.83% respectively on nutrient agar medium. In the 2002 and 2003 field trials the exiacis of A. Indica sed (2.83 aiid 3.28), Piper nigruin seed (2.92 and 3.25), and C'. sinensis peel (3.00 and 3.25) significantly reduced disease severity when compared to untreated controls (5.25 and 4.33) in the two seasons respectively. Cost benefit analysis in the use of piani. exiiacts for disease control in the humid tropics of Eastern Nigeria showed that they could serve as alternatives to synthetic bactericides as a result of their cost effectiveness, availability and safety. Seeds heated at 40-45°C for 20-30 minutes ____I __1I ----------------., ---------.- l__ I ------------I._ I__._I ----- prouuceu lower uisease severny scores in uie neiu wuen compareu Lu umieaieu cOIlUOlS for the two wet seasons. Submerging seeds in hot water at 35°C iffespective of time duration, proved less effective (P < 0.05) in reducing disease severity when compared with untreated controls. Results also showed that hot water treatment of seeds prior to planting could• an effective way of controlling X campestris pv. vesicatoria in field grown tomato.