长鞘卷叶甲化学防治试验

选用7种化学杀虫剂对长鞘卷叶甲成虫进行室内毒力测定,筛选出50%甲好清乳油、40%乐果乳油和90%杀虫单可溶性粉剂等3种杀虫剂的毒力较好,并应用于林间对成虫的防治试验。试验结果表明,分别使用甲好清和乐果的800~1300倍液以及杀虫单的800倍液进行喷雾防治效果较好,用乐果和杀虫单的100倍液进行根灌防治效果较好,用甲好清和乐果的10倍液进行注干防治效果较好,可适当应用于林间防治。     

几种生物农药对茶梢蛾的毒力测定及林间防治试验

为了筛选出最适合防治茶梢蛾的农药,选用6种生物农药和1种化学农药对茶梢蛾幼虫的毒杀力进行了室内测定,并用筛选出的20%乐果乳油、2%阿维.苏可湿性粉剂和3%阿维.氟铃脲乳油这3种毒力较强的农药进行了林间幼虫防治试验。结果表明:使用阿维.苏、阿维.氟铃脲和乐果的2 000倍液进行喷雾防治的效果较为理想,可达到74%～84%的杀虫效果;而用阿维.苏、阿维.氟铃脲和乐果以注干施药法进行防治的杀虫效果并不明显。     

5种植物源杀虫剂对淡竹毒蛾幼虫的毒力及林间防治效果

为筛选出有效控制淡竹毒蛾幼虫的药剂,以制定无公害防治淡竹毒蛾决策,2017年在福建省沙县选用5种植物源杀虫剂,对危害方竹林的淡竹毒蛾幼虫进行室内毒力测定和开展林间防治试验。室内毒力测定结果表明：1%苦皮藤素可溶液、4%鱼藤酮乳油、0.5%藜芦碱可溶性液、1.2%烟碱·苦参碱可溶液、1.5%苦参碱可溶液对淡竹毒蛾幼虫的LC₅₀分别为0.973、1.062、1.216、0.482、0.836 mg/L,以1.2%烟碱·苦参碱可溶液剂对淡竹毒蛾幼虫毒性最强,5种不同植物源杀虫剂对淡竹毒蛾幼虫均有杀虫作用。林间防治效果表明：药后3 d,5种植物源杀虫剂的防治效果均为90%以上,以苦参碱类药剂防治效果最好,2种苦参碱类药剂的林间最佳使用浓度均为1 500倍液;1%苦皮藤素可溶液和0.5%藜芦碱可溶性液林间最佳使用浓度为1 000倍液;4%鱼藤酮乳油林间防治最佳使用浓度为1 200倍液。测试的5种不同植物源杀虫剂均对淡竹毒蛾幼虫有良好的杀虫作用,是无公害防治淡竹毒蛾幼虫的有效药剂。     

黄野螟防治药剂筛选试验

利用浸渍法在室内测定了10种和4种农药分别毒杀黄野螟高龄和低龄幼虫的药效试验,结果表明:对高龄幼虫,1.8%阿维菌素乳油500万倍液,0.5%甲维盐微乳剂500万倍液,森得保可湿性粉剂800倍液,2.5%多杀菌素悬浮剂5 000倍液,90%敌百虫晶体20 000倍液,15%茚虫威悬浮剂3 000倍液和4.5%高效氯氰菊酯乳油1000倍液的致死率均达100%;对低龄幼虫,4.5%高效氯氰菊酯乳油4 000倍液和森得保可湿性粉剂1 000倍液的致死率分别为100%和97.7%。在林间,阿维菌素或甲维盐500万倍液、森得保1 000倍液的杀虫效果均达100%。     

几种药剂对银杏大蚕蛾的毒力测定和防效对比试验

对几种药剂防治银杏大蚕蛾Dictyoploca japonica Butler 2龄幼虫进行了室内毒力测定、林间小区防治试验.室内毒力测定结果表明1.2％烟碱·苦参碱乳油对银杏大蚕蛾2龄幼虫毒力最强,其次为1.8％阿维菌素乳油,最弱的为4.5％高效氯氰菊酯.林间小区防效试验的3种药剂对银杏大蚕蛾2龄幼虫均有很好的防治效果,1.2％烟碱·苦参碱112.5 g/hm2,20％杀铃脲56 g/hm2,25％灭幼脲150 g/hm2为最佳剂量,防效为90.7％ ～92.1％.1.2％烟碱·苦参碱乳油杀虫速率高峰期在第1天;2种仿生物制剂击倒速率较慢,高峰期出现在第10天.1.2％烟碱·苦参碱防治费用最低.     

打孔注药法防治香樟齿喙象幼虫防效试验

香樟齿喙象Pagiophloeus tsushimanus是上海地区危害香樟Cinnamomum camphora的主要害虫之一,该虫主要以幼虫钻蛀香樟主干为害,而传统喷雾防治方法对幼虫防治效果不佳,本文选用打孔注药法针对香樟齿喙象幼虫开展防治,选择10%甲维吡虫啉可溶液剂、1.8%阿维菌素乳油和4.5%高效氯氰菊酯乳油3种农药,每种农药分别配比为原液、5倍、10倍3个浓度梯度,对受害香樟树进行注干防治,针对各处理组连续统计8周防效,通过试验了解不同农药不同浓度对香樟齿喙象的防治效果。试验结果显示防治后8周,10%甲维吡虫啉可溶液剂原液防治效果最好,为77.27%;防效最差为4.5%高效氯氰菊酯乳油10倍液,为46%。     

黄刺蛾的防治技术研究

为了有效控制黄刺蛾(Cnidocampa flavescens Walker)的为害,用10%杀虫葳、40%氧化乐果、4.5%高效氯氰菊酯、25%灭幼脲和1.8%阿维菌素等5种药剂的不同浓度对黄刺蛾进行室内毒力测定和圃间防治试验,并对结果作方差分析。室内外试验结果表明:所选用的5种药剂和浓度对防治效果均有显著影响;林间防治以10%杀虫葳4000倍液喷雾效果最佳,杀虫效果达90%以上。     

缀叶丛螟危害南酸枣的发生规律及防治措施

对缀叶丛螟的形态特征、生活史、生活习性进行观察,并采取室内及林间防治这2种试验方法研究防治措施。结果表明：室内试验选用10％天王星1000倍、90％杀虫单1000倍、20％杀灭菊酯1000倍液效果较好;林间防治应在第1代、第2代幼虫盛发期选用20％杀灭菊酯2000倍、10％天王星2000倍、90％杀虫单1000倍,对3～4龄幼虫进行防治,效果达91％以上,可在大面积爆发时防治应用．     

5种植物源农药防治松丽毒蛾的效果分析

为研究植物源农药及浓度对松丽毒蛾的林间防治效果,于2019年在福建省沙县官庄国有林场的马尾松林分设立试验区,选用0. 6%印楝素乳油等5种植物源农药开展林间喷雾防治松丽毒蛾幼虫试验。结果表明:药后4 d,5种药剂对松丽毒蛾幼虫表现出较好的杀虫效果,0. 6%印楝素乳油、4%鱼藤酮乳油、1%苦参·藜芦碱可溶液、1. 3%苦参碱可溶液和1. 2%烟碱·苦参碱乳油对幼虫的平均死亡率依次为91. 1%、91. 3%、91. 7%、92. 0%和92. 6%,其最适浓度分别为0. 6%印楝素乳油和4%鱼藤酮乳油1000倍液,1%苦参·藜芦碱可溶液1100倍液,1. 2%烟碱·苦参碱乳油和1. 3%苦参碱可溶液1300倍液,在生产防治上可推广应用。     

6种植物源农药防治波纹杂毛虫林间药效分析

为明确6种植物源农药防治波纹杂毛虫的最佳林间配比度和用药量,掌握低空施药技术,在福建省沙县马尾松林建立试验区,开展林间喷雾和喷烟防治试验。结果表明:6种农药的林间喷雾,药后4 d,防治效果均超过90%;最佳林间配比度为:1.3%苦参碱可溶液剂和1.2%烟碱·苦参碱乳油均为1300倍液;1%苦参·藜芦碱可溶液、4%鱼藤酮乳油和0.6%印楝素乳油均为1000倍液,0.5%藜芦碱可溶液为800倍液。2种农药喷烟后3 d,防治效果均超过90%,1.3%苦参碱可溶液和1.2%烟碱·苦参碱乳油与烟雾剂最佳配比度均为1∶9。参试的6种植物源农药可广泛应用于防治波纹杂毛虫幼虫。     

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.     

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.