Weeds are the most prominent of all rice biotic stresses across all the ecologies in terms of yield reduction and increased cost of production. Weed control is therefore one of the most important and suggestive practices for potential rice production. Based on the above, field trials were carried out during 2017/2018 dry season at the Teaching and Research Fadama farm of the Kebbi State University of Science and Technology located at Jega (Latitude 12º21ˈN; Longitude 4º36ˈE) and that of Usmanu Danfodiyo University Sokoto located at Kwalkwalawa (Latitude 130 01ˈN, Longitude 5º09ˈE) to study the correlation between yield and selected parameters of some rice varieties grown in an integrated weed management (IWM) system. Both locations lie within the Sudan Savanna ecological zone of Nigeria. The experiment was done between December, 2017 and August, 2018. The treatments consisted of six (6) weed management options (Solarization/Orizo-plus (3WAT)/Hoe-weeding (6WAT), Round-up/Orizo-plus(at 3WAT)/Hoe-weeding (6WAT), Solarization/Hoe-weeding (3WAT)/Hoe-weeding (6WAT), Round-up/Hoe-weeding (3WAT)/Hoe-weeding(6WAT), Weedy-check and Weed-free) and three (3) rice varieties (Jamila, Faro 44 and Faro 57). The factorial combinations of the treatments were laid out in a randomized complete block design (RCBD) with split-plot arrangement, replicated three times. Weed management options formed the main plots while rice varieties were assigned to the sub-plots. Based on the results of this study, it could be concluded that high weed density in rice field causes poor rice growth and reduces grain yield (r=-0.757). Also, increase in number of leaves, number of tillers, leaf area index, percent productive tillers, length of panicle, weight of panicle and 1000-grain weight resulted to increased grain yield. Therefore, factors that encourage the performance of those parameters can be explored for high rice grain yield.

The study was conducted to assess the incidences of Rice Yellow Mottle Virus disease (RYMVD) in Kebbi State Nigeria, a field survey was conducted in four rice-growing areas of the State. Rice fields were selected randomly at 2 km interval, severity of the disease was assess using arbitrary five-point scale and disease incidence was assessed according to the proportion of the plants showing symptoms. Thirty plants were assessed in each field visited. Symptoms occurred in varying levels of incidence. The presence of RYMV in the collected samples was confirmed using Reverse Transcription Polymerase Chain Reaction (RT-PCR). Mottle/yellowing symptom was found more on the plants assessed (46%) followed by leaf curling (21%), leaf necrosis (09%), leaf deformation (11%) and irregular patches (13%). RYMVD was found highly distributed in the State with average incidence of 54.38%. The highest incidence was recorded in in Yauri (67.50%) followed by Argungu (55.00%), Bagudo (52.50%) and the lowest was recorded in Suru (42.50%). The average symptom severity across all the four Local Governments visited was 2.8, the highest was recorded in Yauri (3.2), followed by Argungu (2.9), Bagudo (2.7) and Suru 2.3. The information obtained in this study would assist rice breeding programs to develop durable RYMV rice resistant cultivars and guide in the identification of RYMVD hot spot locations for seed multiplication trials in Kebbi State.