| Carya cathayensis is a valuable forest crop widely planted in Ningguo city, Anhui Province. Apriona germari and hickory canker disease are the domianant pests which decrease the growth and yield of C. cathayensis, and cause considerable economic losses. In order to control the pest and disease effectively and environmental friendly, laboratory screening of high virulent strains of Beauveria bassiana against A. germari, and field trial for controlling A. germari with B. bassiana was tested by different releasing ways. At the same time, the fungal pathogen of hickory canker disease was identified. The inhibition of fungicides on mycelia growth of the pathogen was tested and the control efficiency was assessed in a field trial. The pathogens of hickory trunk and leaf blight diseases were identified, and the detailed symptoms of the two diseases on the plant were firstly reported.The main contents and conclusions are as follows:1. To assess the potential of B. bassiana as a biological control agent against the longhorn beetle A. germari, eight strains of the fungus that all originally isolated from longhorn beetles were compared and selected by morphologic observation of colony, measurement of germination speed and sporulation ability as well as UV resistance. Finally, the selected strain Bbl898 showed the highest virulence to the target beetle with a corrected mortality of 79.55%, an infection ratio of 54.17%, and a LT50 (time needed for 50% mortality) of 8.12 d at the concentration of 1 × 108 conidia/mL.Field trials for the control of A. germari by B. bassiana were carried out by different releasing ways. Controll efficiencies were compared between the fungal non-woven fiber bands and the fungal conidia suspension. Both treatments caused high mortalities and infection ratios in the beetle wild popution, with a corrected mortality of 78.81% and of 63.97%, and an infection ratio of 33.33% and of 20.00%, respectively. The non-woven fiber bands, which be twisted around the plant trunk, showed a better control effect. The adult mortality and infection rate caused by the band treatment was significantly higher, and the oviposition scars, oviposition and hatch numbers of beetle adults was much lower. The results indicated that the non-woven fiber bands impregnated B. bassiana is an optimal method to control the adult beetles and their next generation effectively.2. The pathogen of canker disease was identified as B. dothidea according to its morphology, pathogenicity and sequence analysis of rDNA-ITS.The pathogen of hickory trunk disease was identified as Pestalotiopsis vismiae by its morphology, pathogenicity and sequence analysis of rDNA-ITS. It is the first report of P. vismiae as a pathogen on Chinese hickory in China. Since the pathogen infections pose a serious threat to C. cathayensis, an appropriate management need be considered for the disease control in this region.Based on morphological features, ITS sequence, and pathogenicity, the pathogen of hickory leaf blight disease was identified as P. mangiferae. It is the first report of P. mangiferae as a pathogen on Chinese hickory, and the identification would allow producers making correct decision on the plant disease management of C. cathayensis.3. The dithianon, carbendazim, copper (II) busic chloride, kresoxim-methy, ltetramycin, azoxystrobin, propiconazole, difenoconazole, chlorothalonil, tebuconazole and prochloraz showed different inhibition on mycelial growth of B. dothidea. Half effective concentration (EC50) of prochloraz and tebuconazole for inhibition of mycelial growth was 0.065 and 0.18 μg/mL, respectively. The results suggested the two fungicides could be used for the canker disease control.Field trials in 2013 confirmed their efficiency. Three different field treatments including trunk injection, scraping disease scab followed by the cover of the fungicides bands and trunk spray showed that prochloraz and tebuconazole had a great effectivity on the control of hickory canker disease. The control efficiecy of trunk injection by prochloraz and tebuconazole was 75.4% and 79.2%, respectively. Followed by scraping disease scab before the fungicides non-woven bands deposited. The control efficiency was 53.0% and 60.4%, respectively. While the trunk spray was only 29.1% and 34.5%, respectively. Further field trial was carried out to compare their efficiency among trunk injection, scraping disease scab before the fungicides bands deposited and the combination of the two treatments. The combination treatment showed significnat synergistic effect on the canker disease control. Two different combination treatments combined different fungicide of prochloraz and tebuconazole in Hule and Xianxia leaded a control efficiency of 84.4% and 85.9%, respectively. The combination treatment had obviously synergistic effect, much better than that of separated control method. |
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