The present investigation was carried out at the experimental farm of Malawi Agricultural Research Station, El-Minia Governorate, Egypt during 2009/2010 and 2010/2011 seasons to investigate the effect of sowing dates (15 th October, 30 th October and 15 th November) and phosphorus fertilizer (0, 15 and 30) kg P2O5 /fed on root rot disease incidence, yield and its quality of three sugar beet varieties i.e. Farida, Kawemira and Montibianco. A split-split plot design with three replications was used, sowing dates were allocated in the main plots, phosphorus fertilizer was assigned in the sub plots while, sugar beet varieties were distributed in the sub-sub plots. The results revealed that sowing date 15 th October significantly reduced root rot disease incidence and increased all quality parameters, i.e. sucrose ,sex, Na, K, alpha amino N,SLM and extractability percentages except purity % as well as productivity traits (top and root yields) in the two growing seasons. The above varieties of sugar beet significantly differed in all studies traits in the two growing seasons. Phosphorus fertilizer significantly effected on all studies traits in both seasons, except sugar yield and (root yield and root fresh weight) in the first season only. Planting Kawemira sugar beet variety when received 30 kg P2O5 / fed in 15 th October significantly increased yields of root and top (ton/fed) in the second season.

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ercospora leaf spot incited by Cercospora beticola Sacc. is a very detrimental fungal disease affecting sugar beet crop production in Egypt as well as sugar yield. The efficacy of four selected commercial biocides i.e., Biobac, Bio-Arc, Bio-Zeid and Plant Guard, was investigated to control Cercospora leaf spot on sugar beet plants in comparison with the recommended fungicide Score as a check difenoconazole fungicide as well as untreated control under field conditions at Sakha Agricultural Research Station, Kafr El-Sheikh Governorate, Egypt. The biocides and fungicide were sprayed at different three spray regimes as two sprays, four sprays or six sprays with 15 days intervals between sprays for such treatment. All tested biocides and Score fungicide led to significant decrease in Cercospora leaf spot disease severity of the treated sugar beet plants in comparison with control treatment. Increasing spraying numbers of the tested biocides or Score fungicide from two times to six sprays per season caused increasing reduction of Cercospora leaf spot severity. Spraying Plant guard, Bio-Zeid and Biobac biocides six times achieved very comparable effectiveness to Score treatment at the same spray regime in the two growing seasons 2015/2016 and 2016/2017, whereas, Bio-Arc was the less effective biocide treatment particularly when sprayed two times per season. All tested biocides at different spraying regimes led to significant increase in values of phenolic compounds, total chlorophyll, (achieved higher quality traits at the end of the season), sucrose (%) and purity (%) and top, root as well as sugar yield quality of sugar beet were significantly increased. The impurities of produced sugar as sodium, potassium and α-amino nitrogen in the juice were significantly decreased in comparison with untreated control during the two growing seasons. Overall results clarified that spraying Score fungicide or Bio-Zeid, Plant guard and Biobac, respectively six times resulted the highest increase of quality traits as sucrose (%) and purity %) and top, root and sugar yields of sugar beet and significant decrease in total amino acid, juice impurities (Na, K and α-a N %), whereas Bio-Arc when applied two times recorded the least effective treatment close to the control during the two growing seasons 2015/2016 and 2016/2017. It was concluded that biocides, Bio-Zeid, Plant guard and Biobac could be sprayed six times/season at 15 days intervals as alternatives to fungicide C 146 EL -MANSOUB et al.

Powdery mildew is a fungal disease that causes a serious reduction in both root and sugar yields in sugar beet areas in Egypt. This study aimed to determine the effect of three water stress treatments namely, IR1 (recommended irrigation times), IR2 (3 withholding irrigation times), and IR3 (4withholding irrigation times) on powdery mildew infection severity and yield components of ten sugar beet varieties. The experimental design was a split-plot design with three replications at Al-Fayoum Governorate, (29°17ˋ N; 30°53ˋ E), Egypt, during 2017/2018 and 2018/2019 growing seasons. Results showed that disease severity varied significantly under the three water stress treatments, which were about 21.02, 18.71, and 16.60 %, respectively. Meanwhile, IR3 (4 withholding irrigation times) is more effective in the control of powdery mildew disease, but it is the lowest one in yield components traits. Varieties i.e. Heba, Pleno, Beta 382 and Sibel registered the lowest values of disease severity percentage (11.77, 13.64, 14.90, and 16.40%, respectively). Withholding of irrigation had a significant effect (P< 0.05) on sugar and root yields so that IR3 water stress treatment registered lower yield (2.78 and 18.53 ton/fed) than IR2 water stress treatment (3.17 and 22.60 ton/fed). As a result, growing sugar beet under IR2 water stress produced higher sugar content and less amino-N and Na accumulation in the root, as compared to IR3 water stress. The lowest disease severity percentage (11.77%) along with the best root yield (22.20 ton/fed) was observed in Heba variety. Sugar beet varieties i.e. Heba, Beta382, and Sibel registered the highest value of oxidative enzymes (catalase, peroxidase, polyphenol oxidase), and we can be recommended these as tolerant disease varieties. Skipping one or more irrigation to reduce the powdery mildew disease was recommended. According to the results, the stress tolerance index (STI) and of geometric mean productivity (GMP) appears to be a suitable selection index to distinguish tolerant sugar beet varieties for water stress. Breeders should focus on the performance of varieties with high root yield in diverse environments and high extractable sugar.

and (1 ridge ON+SB: 3 ridges SB alone) were the best for increasing onion bulb yield and root yield of sugar beet, respectively, in both seasons. The results concluded that onion and sugar beet intercropping could be beneficial in reducing foliar diseases and increasing yield of both crops with a maximized LER and economic return for the farmer compared to each crop cultivated alone.