柑橘溃疡病菌的侵染过程及噻森铜对溃疡病的防治效果

为高效精准防治柑橘溃疡病,本研究对不同成熟度柑橘叶片接种溃疡病菌Xanthomonas citri subsp.cirri后的发病情况进行观察,并在显微镜下观察溃疡病菌侵染叶片的过程,并对不同浓度、不同施用方法下噻森铜的室内防治效果和田间防治效果进行测定,对施用噻森铜后土壤、叶片和果实中的残留进行测定.结果 表明,溃疡...

Infection process of Xanthomonas citri subsp. citri and the control effects of thiosen copper to citrus canker

In order to control citrus canker effectively and accurately, the infection process of sweet orange young leaves by Xanthomonas citri subsp. citri (Xcc) was observed, experiments were conducted in the greenhouse and field to evaluate applying thiosen copper for controlling this disease, and the residues in the soil, leaves and fruits were determined after application of thiosen copper. The results showed that, Xcc infected tender and immature leaves, but not the mature ones. Xcc entered into the leaf tissue cells two-four days after attaching to the leaf surface. The potted sweet orange plants developed no canker symptoms when they were drenched with thiosen copper at 15mL/plant and 20mL/plant 15 d before inoculation with Xcc, developed only light symptoms at 10 mL/plant, and developed severe canker symptoms when they were treated with water. In the field experiment, trees drenched with thiosen copper at 60, 75 and 90 mL/plant had 3.9, 3.9 and 3.7 diseased leaves per plant, 8.4, 8.5 and 8.5 lesions per plant, and 9.4%, 11.5% and 9.6% diseased fruits, respectively. There was no significant difference among the three thiosen copper treatments, but the three treatments all had a significantly lower disease severity than the control-conventional management. By spraying 500×thiosen copper solution before budding, the trees had 16.1 canker spots per plant, not significantly different from those drenched with 60 mL/plant thiosen copper solution, but significantly lower than those under conventional management. The trees sprayed with thiosen copper had 16.8% diseased fruits, significantly higher than those drenched with 60 mL/plant thiosen copper (9.3%), while incidences of diseased fruits under both thiosen copper treatments were significantly lower than those under the conventional management (25.3%). The Cu contents in the soil, leaf and fruit samples from thiosen treatments were not significantly different from those under conventional management, indicating that thiosen copper application did not cause accumulation of Cu. In conclusion, the adverse effects of new shoot growth and rainfall on chemical control of this disease was able to be overcome, and this disease could be effectively controlled by drenching or spraying absorbable organic copper like thiosen copper before budding.