Adaptive Performance of Five Varieties of Hybrid Citrus in Jingzhou Area Hubei Province

In order to understand the growth habits and freeze resistance of the hybrid citrus variety in Jingzhou area, and to provide reference for the introduction of the variety in fruit farmers, and to promote the development of the local citrus industry, the main biological and freeze resistance characteristics of the five hybrid citrus variety were investigated. The results showed that:(1)The growth potential of ‘Wo gan’ and ‘Daya’ were the strongest, followed by ‘Aiyuan 38’ and ‘Chunjian’, and the weakest growth was ‘Buzhihuo’;(2) On the performance of summer and autumn shoots, ‘Daya’ and ‘Wogan’ were the longest, ‘Chunjian’ was moderate, ‘Aiyuan 38’ and ‘Buzhihuo’ were the weakest; (3) On the aspect of freeze resistance, ‘Aiyuan 38’was the strongest, followed by ‘Daya’ and ‘Wogan’, the freeze resistance of ‘Chunjian’ was more weak and ‘Buzhihuo’ was the weakest;(4) On the other aspects, such as the leaf shape, leaf size, color of tender leaf, thorn density, flower size, inflorescence and so on also had the big difference, but the petal number and the petal color were similar. It could be seen that ‘Daya’ and ‘Wogan’ had the best growth potential in Jingzhou area, but their freeze resistance were weak. The growth potential of ‘Aiyuan 38’ and ‘Chunjian’ were in the middle, ‘Aiyuan 38’ had best freeze resistance. The growth potential and freeze resistance of ’Buzhihuo’ in Jinzhou area was the weakest.

Comparative Phylogenomic Analysis Reveals Evolutionary Genomic Changes and Novel Toxin Families in Endophytic Liberibacter Pathogens

Liberibacter pathogens are associated with several severe crop diseases, including citrus Huanglongbing, the most destructive disease to the citrus industry. Currently, no effective cure or treatments are available, and no resistant citrus variety has been found.

Evaluation of Residue Levels of Imidacloprid and Thiamethoxam After Foliar Application to the Citrus Varieties Lane Late, Valencia Late, Rohde Summer, and Nules

Neonicotinoids are used to protect citrus trees against pests. Dissipation and persistence of neonicotinoids in pollen and nectar of citrus trees after foliar applications and their potential exposure to pollinators have not been well characterized. Field studies were conducted using three orange and one mandarin varieties to compare the imidacloprid and thiamethoxam residue levels and their decline in pollen and nectar after treatments in pre-bloom close to flowering period and their persistence 1 yr after treatment. The possible risk to honeybees was assessed. In nectar, thiamethoxam and imidacloprid residues were between 61 and 99% lower than in pollen, depending on the citrus variety or/and the days after treatment when applied close to blooming. At the end of the flowering period, imidacloprid in pollen and nectar was not detected in the mandarin variety after treatment in pre-bloom, whereas for thiamethoxam, no residues were detected in nectar but 10 ng/g was detected in pollen. There were no quantifiable levels of residues for either neonicotinoids in pollen or nectar during the flowering period of the following year. Neonicotinoid residue levels and their decline in nectar and pollen in citrus depended on the timing of applications relative to flowering and on the citrus variety. The absence of neonicotinoid residues 1 yr out after foliar applications in all varieties assayed demonstrated that none of the neonicotinoids tested were persistent. The results could be different in other citrus varieties, and therefore, also the exposure assessment for managed pollinators.