FIRST RECORD for WATERMELON NECROSIS DISEASE on WATERMELON CROP in IRAQ

Abstract

This research was carried out during a severe unknown disorder epidemic wave was spread out on watermelon crop over all Iraqi provinces that causing significant economic losses to the farmers of this crop. The research included conducting a field survey covering about 183 hectares of watermelon fields during the spring agricultural season in four Iraqi provinces; Baghdad, Kirkuk, Erbil, and Penguin/Sulaymaniyah. According to this survey, the disease occurrence percentage ranged from 70-100% in Baghdad, Kirkuk, and Erbil, while it was around 10-20% only in the Penguin/Sulaymaniyah area. It is also noted that plants growing under the shade of trees or long intercropped crops like sunflower, were escaped from the infection. Despite many watermelon varieties cultivated by farmers during the survey year, no resistant or tolerant varieties were observed, and minor differences in their susceptibility were noticed. The disease is diagnosed as Watermelon rind necrosis (WRN) depending on intensive field and laboratory investigations conducted for this purpose. Bacteria were isolated from necrosis spots in the watermelon rind, but the same was isolated also from the healthy tissues in the watermelon rind with less intensity. A high correlation was found between disease occurrence and the amount of difference between night and day temperature during the first month before the fruit ripening. This research finding is considered the first record of watermelon rind necrosis (WRN) disease on the watermelon crop in Iraq