矢尖蚧的重要天敌二双斑唇瓢虫的研究

二双斑唇瓢虫是多种果树蚧类的重要捕食性天敌之一。该虫在贵阳一年发生4代,世代重叠。单雌产卵量平均为94.41粒,最多465粒。成虫寿命平均为124.71天,最多222天。该虫与矢尖蚧的发生期较为一致,能在柑桔园中形成比较稳定的种群,对矢尖蚧种群有较大的控制作用,田间对矢尖蚧的捕食率以8,9月间为最高,可达48.85％。     

苏云金芽孢杆菌防治柑桔害虫的后效作用

1985年在广西隆安县从未施过Bt菌剂的柑桔园中喷洒Bt菌剂(Bt5a5b).1986年对该园的土壤和柑桔叶片取样分析,结果表明,施菌区土壤及叶片的Bt(H5a5b)检出率均高于不施菌剂的对照区。1987年检测果园的鳞翅目害虫,施菌区活虫的Bt检出率为51.4％,其中Bt(H5a5b) 占60.2％,死虫的Bt检出率为81.3％,其中Bt(H5a5b)占67.1％。对照区活虫Bt检出率为20.5％,其中Bt(H5a5b)占34.3％,死虫的Bt检出率为35.7％,其中Bt(H5a5b)占10％。说明施用菌剂两年后,果园中仍残留一定量的Bt,对害虫有致死的作用。     

捕虱管蓟马生物学的初步研究

捕虱管蓟马是柑桔盾蚧卵和幼蚧的重要捕食性天敌。在广州地区各虫态均可越冬。该虫常在隐蔽场所活动和取食。种群数量在5月上旬有一显著的高峰(22.1头/叶),此后虫口数量就逐渐下降。在室内(平均气温22～27℃)条件下,完成一个世代需35.4天,产卵量为22.2±6.5粒。雌雄性比平均为3:1。成虫寿命雌17.4±5.6天,雄7.4±4.2天。雌成虫在室内平均一天能捕食褐圆蚧雌虫3.3头,或糠片蚧8.4头。当食料缺乏时,有自相残杀的习性。     

柑桔“以螨治螨”生物防治技术研究

柑桔病虫害发生种类多，为害重，生产上喷药次数多，果品存在农药残留高，为了使我市柑桔达到无公害生产水平，减少化学农药使用量，提高柑桔品质，笔者通过释放捕食螨Amblyseius spp．建立捕食螨种群，同时结合使用生物农药和电子灭虫灯，以及白花草Ageratum conyzoides L．等栽培措施，达到了长期持续控制柑桔病虫发生的目的，而且减少我县柑桔生产的农药残留问题，降低生产成本，减少环境污染。     

Ribosomal DNA Sequence Comparisons of Colletotrichum Graminicola from Turfgrasses and other Hosts

The 5.8S ribosomal gene and the flanking internal transcribed spacers (ITS) 1 and 2 from Colletotrichum graminicola isolates causing anthracnose disease of Agrostis palustris and Poa species were sequenced. Although bootstrap support was not high, two major groups were observed with both UPGMA and parsimony algorithms, one containing isolates from A. palustris and another with isolates from Poa spp. The ITS sequences were also compared with those of isolates of C. graminicola and C. sublineolum from Sorghum spp., Zea mays and Rottboellia cochinchinesis as well as other Colletotrichum species. Except for one isolate from P. annua in Texas, the ITS1 and ITS2 sequences of turfgrass isolates always grouped separately from C. graminicola or C. sublineolum from non-turfgrass hosts with high bootstrap support. ITS sequences of the turfgrass isolates were more similar to those of other species of Colletotrichum, such as C. coccodes and C. dematium, than they were to C. graminicola isolates from other hosts. Turfgrass isolates have ITS sequences which are not identical to those of isolates from Zea mays and Sorghum species demonstrating diversity among fungi conventionally classified as C. graminicola.     

6个日本脐橙优良品种对柑桔溃疡病的抗性调查

在广西象州柑桔溃疡病疫区引种试栽了6个日本脐橙品种，丹下，铃木，森田，清家，白柳，吉田。经３年调查观察，发现品种间抗病性和丰产性有不同程度的差异，其中以丹下表现最好，可在疫区适当发展这一优质脐橙品种。     

桔园柿广翅蜡蝉卵块空间分布图式

柿广翅蜡蝉在某些柑桔产区新上升为主要害虫。我们于1986年7月间在宜昌柑桔产区对其卵块分布图式进行了调查,通过10组资料分析,得如下结果:(1)由比较频次法测得卵块在桔园呈负二项或截尾负二项分布。(2)由聚集强度测定方法测得卵块在桔园呈聚集分布图式,其分布的基本成份是疏松的个体群,个体群的分布是聚集的,个体内的分布是随机的。(3)由 IwaoM~*指标法求得个体群大小为1～3株(10组资料平均为1.7株)桔树所占面积。(4)由 Blackich 的λ值测得,卵块密度大于6的9组资料其聚集是由于卵块自身聚集行为习性造成(由成虫产卵行为决定),或某些环境因子作用引起。而有一组密度为2.4的资料,其聚集可能完全由于某些环境条件的作用而引起。     

Effect of ammonium carbonate and sodium bicarbonate on anthracnose of papaya

Colletotrichum gloeosporioides is the causal organism of anthracnose inCarica papaya L. (papaya, papaw). The effect of ammonium carbonate (3%) or sodium bicarbonate (2%) in aqueous solution or when incorporated into a wax formulation on anthracnose severity in inoculated or naturally infected fruits was examined. Both salts had significant effects, but that of ammonium carbonate was greater than that of sodium bicarbonate in controlling anthracnose. Ammonium carbonate (3%) incorporated into the wax formulation effectively reduced anthracnose incidence by 70% in naturally infected papaya and extended the storage life by maintaining the firmness, color and overall quality of the fruit in low temperature storage (13.5°C) and 95% r.h. for 21 days followed by 2 days under marketing conditions. The mode of action of ammonium carbonate on the control of anthroacnose appears to bevia complete inhibition of radial mycelial growth and conidia germination. http://www.phytoparasitica.org posting Aug. 14, 2002.     

Reclassification of an isolate of Guignardia citricarpa from New Zealand as Guignardia mangiferae by sequence analysis

Citrus black spot was recorded as present in New Zealand in international databases on the basis of one isolate (ICMP 8336) identified by morphological features as Guignardia citricarpa . This isolate was from a soft rot, not a typical symptom of citrus black spot, on a Seminole tangerine fruit grown in the northern region of New Zealand. Sequence analysis of the internal transcribed spacer (ITS) region (ITS1, 5·8S and ITS2) showed that this isolate was 99% identical to the ITS region of G. mangiferae , a closely related saprotroph. Despite climatic conditions being suitable for this disease, citrus black spot symptoms have never been seen on citrus fruits grown in New Zealand. Thus the absence of symptoms on citrus in New Zealand is probably because G. citricarpa is not present. On the basis of these results, the record of citrus black spot occurring in New Zealand should be re-examined.     

Resistance in water yam (Dioscorea alata) cultivars in the French West Indies to anthracnose disease based on tissue culture-derived whole-plant assay

Reactions of 60 water yam ( Dioscorea alata ) cultivars to three isolates of the yam anthracnose fungal pathogen ( Colletotrichum gloeosporioides ) were evaluated using tissue culture-derived whole-plant assay. Three disease parameters: single score on a scale of 0–6 at the seventh day after inoculation (SD7); area under the disease progress curve (AUDPC); and disease progress rate ( R _d) were compared, and cultivars were classified into disease-response groups using a rank-sum method based on AUDPC scores for the two most virulent isolates. A wide range of variation in resistance of the D. alata cultivars, and significant effects of pathogen isolate and isolate–cultivar interactions, were observed for all disease parameters. The three disease parameters were positively correlated; however, four cultivars showed great dispersions from the regression lines for comparisons of SD7 with the multiple assessments based AUDPC and R _d. The 60 cultivars were separated into resistant ( n  = 12), moderately resistant ( n  = 19), moderately susceptible ( n  = 18) and susceptible ( n  = 11) groups. The potential of the tissue culture-derived whole-plant assay to resistance breeding programmes and further understanding of the yam anthracnose pathosystem is discussed.