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Poster: Biology & Disease Mgmt: Cultural Control


Effective treatments for eradication of Xanthomonas cucurbitae in pumpkin seed
X. ZHANG (1), M. Babadoost (2) (1) Department of Crop Sceinces, University of Illinois, U.S.A.; (2) Department of Crop Sciences, University of Illinois, U.S.A.

Bacterial spot, caused by Xanthomonas cucurbitae, has become a serious disease of pumpkin in Illinois and other states in the Midwest. X. cucurbitae infects leaves and fruit. Fruit infection often results in fruit rot. More than 90% of fruit infection with X. cucurbitae in pumpkin fields has been reported. X. cucurbitae is considered as a seed-borne pathogen, hence developing an effective seed treatment to eradicate the pathogen in seed is essential. This study was conducted to develop reliable treatments for eradication of X. cucurbitae in seed. Hot-water, HCl, and NaClO treatments for eradication of X. cucurbitae in ‘Howden’ and ‘Dickinson’ pumpkins were assessed. Seed were treated in water with 49, 50, 51, 52, 53, 54, 55, and 56°C, for 5, 10, 15, 20, 25, and 30 min at each of the temperatures. Treatment at 55°C for 10 min eradicated X. cucurbitae in both naturally-infected and artificially-inoculated seed without significant adverse effects on seed germination or seedling vigor. HCl treatments included 0.5, 1.0, and 2.0% HCl solutions for 10, 20, 30, 40, 50 and 60 min. The most effected HCl-treatment was 0.5 % concentration for 40 min, which eradicated X. cucurbitae in the seed without any negative effect on seed germination or seedling vigor. For NaClO treatment, pumpkin seeds were soaked in NaClO solution with concentration of 0.5, 1, 1.5 and 2% for 1, 2, 3 and 4 min. None of the NaClO treatments completely eradicated X. cucurbitae in pumpkin seed.