绿色威雷防治毛竹卵圆蝽的试验

绿色威雷（触破式微胶囊水悬剂）是防治大型害虫的新型药剂，通过防治卵圆蝽Hippotiscus dorsalis(Stal.)若虫小区试验和大田试验，施药后42天小区试验平均死亡率达96.8%，大田试验虫株率为0，防治效果显著，并克服了“竹腔注射”防治法降低竹材质量的缺点，有较好的推广应用前景。     

樟颈曼盲蝽防治试验初报

采用25g/L高效氯氟氰菊酯、522.5g/L氯氰.毒死蜱、10%高渗敌敌畏和10%氯噻啉对樟颈曼盲蝽进行防治试验,结果表明,高效氯氟氰菊酯具有较好的防治效果,其0.1%药液防治效果达100%,0.067%药液校正死亡率达93.3%。其次是氯噻啉0.1%药液和氯氰.毒死蜱0.1%药液,防治效果分别为90.6%和89.5%。经林间大面积防治,施用高效氯氟氰菊酯和氯氰.毒死蜱农药后,林间平均虫口密度降至1～2只/网,能有效控制樟颈曼盲蝽的发生与危害。     

直升机喷洒微囊剂防治松褐天牛的药效试验

以诱捕到的松褐天牛成虫总数来测定8%氯氰菊酯触破式微囊悬浮剂(绿雷二代)和3%噻虫啉缓释型微囊悬浮剂防治对松褐天牛的飞机防治效果。结果表明:8%氯氰菊酯触破式微囊悬浮剂和3%噻虫啉缓释型微囊悬浮剂都对松褐天牛有较强的毒力,但8%氯氰菊酯触破式微囊悬浮剂药效持效期更长,可高达1个月以上;在后续的田间试验防治松褐天牛试验中,两种药剂设置用药量分别是6.67 mL/hm2和13.34 mL/hm2,和空白对照3个处理,分别设3个重复。两种药剂结果对比发现,8%氯氰菊酯触破式微囊悬浮剂比3%噻虫啉缓释型微囊悬浮剂表现出更好的速效性、持效性和综合防效的稳定性;8%氯氰菊酯触破式微囊悬浮剂对松褐天牛的虫口减退率始终保持在90%-98%之间,3%噻虫啉缓释型微囊悬浮剂对松褐天牛成虫虫口减退率仅在药后6～22 d期间防效达到90%以上。     

早竹林内竹小蜂药物喷洒防治试验

早竹作为笋用竹种,具有可观经济价值。近年来,随着早竹林经营年限不断增长,其病虫害发生在逐年加重,成为影响早竹林经营的重要危害。南京高淳地区,刚竹泰广肩小蜂和竹泰广肩小蜂对早竹林生长、产笋等产生危害。以4种不同化学药剂(噻虫啉,吡虫啉·甲氨基阿维菌素,氯氟氰菊酯和林得保杀虫粉剂)对早竹林进行喷洒试验,结果表明:药剂效果以3%噻虫啉微囊悬浮剂最为显著,其中稀释2 000倍的噻虫啉效果最佳,短枝受害率控制在3%左右;10%吡虫啉·甲氨基阿维菌素苯甲酸盐可溶液剂和林得保的效果次之,短枝受害率下降近2%;10%高效氯氟氰菊酯微囊悬浮剂试验效果最差。     

林间药剂喷雾防治新疆光肩星天牛的药效试验

通过选择48%乐斯本、5%锐劲特、2.5%溴氰菊酯、8%触破式微胶囊剂、2%噻虫啉微胶囊悬浮剂等5种高效低毒农药对光肩星天牛(Anoplophora glabripennis Motschulsky)进行喷雾防治试验,结果表明:防治效果较理想的为8%触破式微胶囊剂、2%噻虫啉微胶囊悬浮剂和5%锐劲特3种药剂,防效分别达到80.7%、78.1%和76.3%。     

三种粉剂农药防治竹卵圆蝽试验

为解决竹卵圆蝽Hippotiscus dorsalis(Stl)在毛竹高处危害,防治困难的问题,选用森得保(0.18%阿维菌素·Bt活芽孢100亿/g)、林得保(0.3%阿维菌素·Bt活芽孢100亿/g)和噻虫啉3种农药粉剂喷粉防治上竹后的竹卵圆蝽。结果表明,3种粉剂均取得较好防治效果,其中森得保效果最好,15 d虫口减退率达95.8%,成本也适中。因此,选用森得保粉剂喷粉防治上竹后的竹卵圆蝽值得在生产中推广。     

三种杀虫剂防治云斑天牛的林间药效试验

摘要：本文研究比较了三种杀虫剂防治杨树云斑天牛的试验效果。结果表明,48％噻虫啉悬浮剂、10％高效氯氟氰微囊悬浮剂和8％氯氰菊酯微囊剂对云斑天牛都具有较好的防治效果。药后3天,48％噻,虫啉悬浮剂的防效为72．5％～77．5％;8％氯氰菊酯微囊剂的防效为70．0％～72．5％。药后14天,48％噻虫啉悬浮剂的防效为89．9％～96．2％;10％高效氯氟氰微囊悬浮剂防效为73．8％～95．0％;8％氯氰菊酯微囊剂的防效为88．6％～91．1％。因此,这三种杀虫剂均可用于杨树云斑天牛的防治。     

三种杀虫剂对板栗透翅蛾防治研究

本试验选用高效氯氟氰菊酯、啶虫脒和氧化乐果对泰安市徂徕山林场内板栗透翅蛾进行防治。结果表明采用注射法施用3%的啶虫脒乳油防治效果最好,施药15天后平均防效为94.7%,40%氧化乐果乳油的平均防效为91.3%,2.5%高效氯氟氰菊酯乳油的平均79.6%;直接涂抹药剂比注射法施药防效略低,三种药剂的平均防效分别为93.1%、89.2%、78%。     

噻虫胺·高效氯氟氰菊酯微囊悬浮剂防治落叶松毛虫高龄幼虫的试验效果

落叶松毛虫(Dendrolimus superans)在春季大发生时多为3~6龄,可造成严重危害。通过使用噻虫胺·高效氯氟氰菊酯微囊悬浮剂对春季高龄幼虫进行防治试验,结果表明:使用该药剂稀释1000倍液防治3~6龄幼虫见效快、效果好;虫口密度不高时可采用1800倍液喷雾施药;防治3龄以下幼虫,可稀释2500倍液喷雾防治。     

白蜡外齿茎蜂防治试验研究

进行白蜡外齿茎蜂Stenocephus fraxini成虫和幼虫防治试验,结果表明:在成虫羽化高峰期喷药防治成虫,2.5%高效氯氟氰菊酯2500倍液,1.8%阿维菌素1500倍液,3%噻虫啉1500倍液速效性好。在幼虫孵化初期灌根防治幼虫,25%噻虫嗪1000倍液和20%呋虫胺2000倍液防效最好;打孔注药防治幼虫,5%和10%吡虫啉原液、5%啶虫脒原液防效最好;毒死蜱不适宜于打孔注药使用。     

Growth of Phlebiopsis gigantea in wood of seven conifer species

Heterobasidion parviporum and Heterobasidion annosum are widely distributed root‐rot fungi that infect conifers throughout Europe. Infection of conifer stumps by spores of these pathogens can be controlled by treating fresh stumps with a competing non‐pathogenic fungus, Phlebiopsis gigantea. In this study, growth of three Latvian strains of P. gigantea and the biological control agent ‘Rotstop’ strain was evaluated in stem pieces of Norway spruce, Scots pine, lodgepole pine, Douglas‐fir, Weymouth pine, Siberian larch and Sitka spruce. The growth rates of one H. parviporum and one H. annosum isolate were also measured in the same stem pieces. The growth rate of P. gigantea varied greatly in wood of different conifer species. It was higher in the three pine species, lower in Norway spruce and lowest in Sitka spruce and Siberian larch, and in Douglas‐fir, this fungus did not grow. The largest area of wood occupied by P. gigantea was in lodgepole pine. Growth of Latvian isolates of P. gigantea in the wood of Pinus and Picea species was comparable to that of the Rotstop isolate. Consequently, stump treatment with local P. gigantea isolates should be recommended. However, our results suggest that Douglas‐fir stump treatment against Heterobasidion by P. gigantea may be ineffective and other stump treatment methods should be considered.     

Growth of Mixed Birch-Coniferous Stands in Relation to Pure Coniferous Stands at Similar Sites in South-eastern Norway

Mean age, mean and top heights and yield were studied in 20 mixed stands of birch ( Betula pubescens Ehrh. and B. pendula Roth) and Picea abies (L.) Karst. and nine mixed stands of birch and Pinus sylvestris L. in south-eastern Norway. Each mixed stand and the adjacent pure coniferous stand (control) were growing under the same site conditions and had not been commercially thinned. There were no significant differences in mean age at breast height or in top heights between birch and conifers in the mixed stands, while mean height was significantly higher for birch than for spruce. A growth index was calculated based on total volume and age at breast height. For the spruce sites the growth in young mixed stands (birch < 17 m) was superior to that of pure spruce, while the difference was insignificant in older stands. The growth index correlated positively with the ratio between generatively and vegetatively regenerated birch trees, and negatively with the age of the oldest species in the mixture and with site quality. For the pine sites there was no significant difference in the growth index between mixed birch-pine and pure pine stands. A mixture effect of birch on the volume yield of spruce or pine could not be demonstrated.     

Defoliation by the Needle-shortening Pine Gall Midge,Thecodiplosis brachyntera,on Pines in Central Sweden

An outbreak of the needle-shortening pine gall midge, Thecodiplosis brachyntera , occurred on Scots pine, Pinus sylvestris (L.) and lodgepole pine, P. contorta (Dougl.) in central Sweden during 1995-1998. The larval feeding of T. brachyntera kills current-year needles and heavy infestation causes severe defoliation. A pattern of fluctuating defoliation among years and sites was found on both pine species. Defoliation was evenly distributed in the crown of P. sylvestris during years of high as well as low infestation; apical whorls had as much defoliation as basal whorls. In P. contorta , however, there was a tendency for defoliation to be concentrated on branches in the most apical whorls. Growth ring increments on P. sylvestris with high levels of defoliation (71%) did not differ from trees with moderate levels (26%) of defoliation. Shoot lengths were significantly shorter, however, on heavily infested trees the year after defoliation.     

Decomposition and nutrient loss from prunings of different contour hedgerow species in tea plantations in the sloping highlands of Sri Lanka

Contour hedgerows of multipurpose tree species in the sloping tea lands of Sri Lanka are expected to reduce soil erosion and also add significant amounts of plant nutrients to the soil via periodic prunings. The objective of this experiment was to characterize the biomass decomposition pattern and quantify the amount of nutrients added through prunings of six tree species (Calliandra calothyrsus, Senna spectabilis, Euphatorium innulifolium, Flemingia congesta, Gliricidia sepium and Tithonia diversifolia) currently being used in hedgerows associated with tea. Withered leaf and stem prunings (50 g) were enclosed in 2-mm litter bags, placed at 5-cm depth and retrieved after one, three, six, nine and 12 weeks. Loss of initial dry weight, N, P and K was measured. Single exponential decay function adequately described both dry weight and nutrient loss. Tree species differed significantly in their rate of breakdown with decomposition constants (k) varying from 0.0299 to 0.2006 week⁻¹ for leaves and from 0.0225 to 0.0633 week⁻¹ for stems. Gliricidia showed the highest k for leaves with the rest in the following descending order: Senna > Tithonia ≥ Euphatorium > Calliandra > Flemingia. A similar pattern was observed for loss of all nutrients with Calliandra and Flemingia always having lower k values than the rest. Although N immobilization was not observed, immobilization of P and K was observed during the first week of incubation in some species, particularly in stem prunings. Annual biomass of prunings differed significantly between tree species in the following descending order: Calliandra > Senna > Flemingia > Tithonia > Gliricidia > Euphatorium. Calliandra added the greatest amount of nutrients annually to the soil with Euphatorium adding the least. Calliandra prunings provided the annual total K requirement and 49% of the N requirement of mature tea. However, none of the species provided more than 5% of the P requirement. It is concluded that among the tree species tested, Calliandra and Flemingia are the most suitable for contour hedgerows in tea plantations of this agroclimatic region because of their higher soil nutrient enrichment capacity and slower decomposition rates which would minimize leaching losses. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effects of Seed Weight and Seed Type on Early Seedling Growth of Pinus sylvestris under Harsh and Optimal Conditions

The effects of seed weight and seed type on seedling growth of Pinus sylvestris (L.) were studied by seeding individually weighed orchard and stand seed in different mixtures under harsh (direct seeding in field) and optimal (seeding in nursery) conditions. In the nursery experiment an increase in the seed weight from 3 to 7 mg increased the seedling height by 10-27% and total weight by 27-113%, and decreased the height/diameter ratio by 5-6% after 2 yrs. With elimination of seed weight effects, orchard seedlings were 2% taller than stand seedlings in year 2. Without elimination of seed weight effects, orchard seedlings were 7-13% taller. In the field experiment an increase in the seed weight from 3 to 7 mg increased seedling height by 18-65%, stem volume by 81-274% and the number of top-buds by 23-34% in year 5. After elimination of seed weight effects, orchard seedlings were 7-13% taller than stand seedlings and without elimination of seed weight effects 20-21% taller after 5 yrs. Even after elimination of both seed weight and genetic effects orchard seedlings were 3-9% larger than stand seedlings in the field experiment. In conclusion, the influence of seed weight and seed type on growth traits and slenderness is highly significant and the influence seems to be greater in harsh conditions.     

Modelling of adequate pretwist for obtaining straight timber

Abstract

Wood in general and wooden studs in particular are often distorted owing to uneven shrinkage during the drying process in the sawmill. Twist is often the most detrimental of all types of distortion, and it is caused by spiral grain in combination with variations in moisture content. For sawmills, the objective is to produce dried, straight boards, and one method of dealing with boards with excessive spiral grain is to sort them out and then dry them in a pretwisted position to obtain straight boards after drying. A model using the finite element (FE) method for the simulation of drying twist distortions was first calibrated against laboratory experiments in which boards were dried with and without restraints and pretwists. After the calibration, the FE results were compared with industrial test results for boards that were dried without restraints or with restraints with zero pretwist, i.e. straight restraints. The FE model used an elastic–ideally plastic material model to obtain permanent deformations. The calibration was to set the yield stresses so that there was a good match between FE results and results from the laboratory experiments. The comparison between the industrial test results and the FE results showed that the FE model is capable of realistic simulations of drying boards with and without restraints and presumably also pretwists.     

Potential to harness superior nutritional qualities of exotic baobabs if local adaptation can be conferred through grafting

Baobab leaves form an important part of the local diet in Sahel countries and elsewhere in Africa. Existing leaf nutritional data and agroforestry performance information are based solely on Adansonia digitata L., the baobab of continental Africa. The introduction potential of Adansonia species from the center of diversity in Madagascar and from Australia remains untapped. To assess this potential, the mineral contents and B₁ and B₂ vitamin levels of dried baobab leaves were determined for five-year old trees of A. digitata, A. gibbosa (A. Cunn.) Guymer ex D. Baum, A. rubrostipa Jum. & H. Perrier (syn. A. fony Baill.), A. perrieri Capuron and A. za Baill. grown in an introduction trial in Mali. Nutritional data were evaluated against survival and vigor to identify promising germplasm. Leaf vitamin and crude protein contents were highest in the Madagascar species, especially A. rubrostipa (B₁ 88 mg 100 g⁻¹, B₂ 187 mg 100 g⁻¹, protein 20.7% dry weight). However, the local species far outperformed the introductions in survival, tree height, basal diameter and resistance to termites. We suggest grafting as a way of harnessing the vigor of well-adapted local baobab varieties to the superior nutritional profiles of A. rubrostipa and others. Cross-species grafting tests in Adansonia were successful, thus creating new agroforestry possibilities with different scion/rootstock combinations.     

Biogeochemical impacts of clearfelling and reforestation on blanket-peatland streams: II. major ions and dissolved organic carbon

Streams and drains in blanket-peatland forest in western Ireland were sampled weekly over 5 years, 1996–2000, using continuous, depth-proportional passive sampling. Analysis was for pH, alkalinity by Gran titration, anions by IC, metals by ICP, aluminium speciation by loaded-resin exchange, and dissolved organic carbon (DOC) by absorbance at 320 nm.

Effects of felling are identified graphically from two forest drains whose catchments (both about 1 ha) were clearfelled, and partial clearfelling of one larger catchment (somewhat over 1 km²), in summer 1999. Calcium concentrations and alkalinity were increased in the drain- and streamwater from the felled areas. The pH was increased in drains, while in the larger stream, pH range decreased while the mean increased. Phosphorus increased markedly with clearfell, in the absence of recent fertilising, and also increased with fertilising; these results are reported in an accompanying paper. Ammonium-nitrogen concentrations were increased in the two drains with felling, and temporarily decreased in the larger stream. Nitrate increased in some cases. Potassium and manganese concentrations also increased. Concentrations of DOC and organic monomeric aluminium increased gradually, subject to a continuing strong annual cycle. There were no clearfelling effects on concentrations of solphate, suspended solids or inorganic monomeric aluminium. In the two drains (fully clearfelled), concentrations of sodium, chloride and magnesium, and conductivity, were all reduced after felling. Fertilising effects other than for phosphorus were indistinct.

Effects of the combined clearfell–reforestation treatment were testable statistically, using randomised intervention analysis, between two larger streams (1 km²) as a treatment–control comparison. There were statistically significant positive responses in streamwater concentrations of nitrate, potassium, calcium, DOC and aluminium fractions. The implications for management practice depend on whether the loss of nutrients is sustainable for future crop productivity, and whether critical limits and loads of receiving ecosystems are exceeded.     

Effect of Drought on Growth and Mortality of Actively Growing Norway Spruce Container Seedlings Planted in Summer

Survival, root egress and height growth of 13-month-old actively growing Norway spruce ( Picea abies (L.) Karst.) container seedlings exposed to preplanting drying treatments (0, 4, and 8 days) and postplanting drought periods (1, 2, 3, and 4 weeks) were studied in the field between 5 July and 18 August 1999. The mortality of seedlings increased and the height growth and root egress decreased throughout the postplanting drought period. Postplanting performance was also affected by preplanting drying treatments. The results indicate that no risk of excessive mortality and growth restrictions occurs when actively growing seedlings are planted in summer, provided that seedlings are well watered before planting and the drought period does not exceed 3 weeks.     

Rehabilitation of diseased cacao fields in Peru through shade regulation and timing of biocontrol measures

The objective of this case study was to test the effectiveness of biocontrol for the rehabilitation of abandoned, diseased (moniliasis, witches' broom and black pod) cocoa and to develop testable hypotheses regarding the effect of shade and biocontrol timing. Three trial fields differed in their shade regimes. Biocontrol was administered starting either at flowering or pod filling. Disease incidence and yield were compared with cultural control alone. Biocontrol reduced moniliasis from 49% to 25%, independent of the shading regime and application time. Witches' broom was most severe without shade and unaffected by biocontrol. No significant effects on black pod were observed. Although biocontrol increased percentage healthy fruit independent of shading and timing, only the shaded plot with biocontrol from flowering onwards responded with increased yield. Our hypothesis is: 'In the rehabilitation of abandoned cacao, only fields under sustainable shade management and early onset of biocontrol can realise their production potential.' This revised version was published online in June 2006 with corrections to the Cover Date.