苹果树早期落叶的原因与防治方法

<正>1苹果树早期落叶的原因(1)不同生长势影响树体早期落叶。树势衰弱,树体密植,枝量大,通风透光不良的苹果树落叶早且落叶严重,而树势强壮,通风透光好的苹果树落叶晚且轻。(2)病害引起落叶。引起苹果树早期落叶的病害主要有褐斑病、轮纹病和斑点落叶病等几种,在叶片上形成各种病斑,造成早期大量落叶,严重削弱树势。其中以褐斑病     

苹果早期落叶病的防治

苹果早期落叶病是褐斑病、褐纹病以及斑点病等病的统称。苹果遭受上几种病害菌的侵害，能使苹果树早在8、9月份就大量落叶变黄，所以称为早期落叶病，亦称落叶病、黄叶病。其中以褐斑病危害最重。早期落叶病常使果实不能很好长大成熟以至早落果，促使果树秋季开花，树势衰退。树的寿命减短，影响产量。褐斑病除危害苹果叶片外，有时果实也能染病，苹果品种中秋力蒙、黄海棠等染病较重，新品种有红黄元帅、红富士等。褐斑、褐纹及斑点病都是以孢子或菌丝在被害部叶、枝、果实等处越冬，次年借风、雨传播，长距离传播主要是带病的苗木。褐斑病…     

苹果早期落叶病的发生与防治

苹果早期落叶病的发生与防治靳爱荣，李淑恩（正定县林业局森检站０５０８００）近两年来，苹果早期落叶病是石家庄市范围内苹果生产上的主要病害之一，它主要包括苹果褐斑病、灰斑病、圆斑病和轮斑病，其中生产上表现最为严重的是褐斑病和灰斑病，它能使叶片大量提前脱落...     

杨树早期落叶原因分析与防治对策

造成杨树早期落叶的原因主要是抗病性差,遇到特殊的气象条件,导致杨树黑斑病严重发生。为防止早期落叶,应从营林措施入手,选育抗病品种,大力营造混交林,适时防治病虫害。     

苹果、梨树冬春病虫害的综合防治六则

从秋季落叶后到春季发芽前，是苹果、梨树的休眠期。这一时期病虫越冬场所比较集中，龄期一致，冬眠时间长，活动能力弱。此期加强防治，省工、省药、效果好，对减轻果园全年的病虫危害，能起到事半功倍的作用。 　　1．清园。许多病源和害虫如苹果、梨腐烂病、轮纹病、早期落叶病、梨木虱、梨网蝽、卷叶虫等，都在树下的枯枝落叶或杂草中越冬。因此，在落叶后及时将园内的枯枝落叶和杂草清扫干净，集中深埋或烧毁，以消灭越冬病源、虫源。 　　2．耕翻。在封冻前或早春解冻后，耕翻土地，破坏害虫的越冬场所，将越冬害虫翻在地表风干冻死或…     

苹果树根部病害防治技术

近几年，苹果树根部病害有逐年加重的趋势。不少果园出现了严重的早期落叶现象，给根部病害的发生提供了有利条件。故应引起足够的重视，加强综合防治。     

落叶松早期落叶病防治技术

落叶松早期落叶病主要来源于病菌感染,病害的主要症状为大量落叶。对落叶病进行及早防治,可以提升落叶松林木品质、节省种植管理成本、完善病虫害防治技术。笔者从湿度、地形、林分状态3方面分析了落叶松落叶病发病原因,从合理采伐、林地清理、加强林区管理等方面总结了落叶松落叶病防治技术,以期为今后植树造林防治落叶松落叶病提供技术参考。     

无六六六粉烟剂防治落叶松早期落叶病试验

落叶松早期落叶病,是我国北方八省落叶松林的主要病害。林业部安阳林业制药厂,为了控制六六六粉农药对自然环境的污染,研制出新型无六六六粉杀菌烟雾剂,同辽宁省林科所配合,进行了防治落叶松早期落叶病的试验,现总结如下。     

5种中草药防治花椒早期落叶落果病药效试验

选用5种中草药(桑白皮、马齿笕、丁香、藿香、蛇床子)提取液进行防治花椒早期落叶落果病效果试验。结果表明,5种中草药对早期落叶落果病菌均有明显的抑制和杀菌作用,其中丁香、蛇床子提取物对花椒早期落叶落果病防治效果最佳,施药后落叶落果病感染率比对照分别下降59.76%、49.1%;脱叶率低于3.5%以下,相对防效高于90.5%,落果率低于1.7%以下,相对防效高于91.1%;株产干果皮比对照平均增产29%~86.5%,既防病治病,又能营养复壮树体,无抗药性,无毒无残留。     

杂种落叶松的识别技术

杂种落叶松在抗早期落叶病、抗寒性等方面具有一定优势,冻害指数较日本落叶松低70%,早期落叶病发病率较兴安落叶松低15%、感病指数下降15%。根据针叶形态和一些生理生化手段可将杂种落叶松和亲本区分开来。     

Species differences in timing of leaf fall and foliage chemistry modify nutrient resorption efficiency in deciduous temperate forest stands

Extensive variation in fractional resorption of mineral elements from plant leaves is still not fully understood. In multi-species forest stands, species leaf fall phenology and leaf constitution may significantly modify the timing of nutrient return to the soil and overall plant nutrient loss. We studied leaf fall and nutrient loss kinetics, and leaf composition in three natural, temperate, deciduous broadleaf forest stands to determine the role of timing of leaf abscission and nutrient immobilization in cell walls on nutrient resorption efficiency of senescing leaves. Nitrogen (N), phosphorus and potassium contents decreased continuously in attached leaves after peak physiological activity during mid-season. Changes in nutrient contents of attached leaves were paralleled by decreases in nutrient contents in freshly fallen leaf litter. In different species and for different nutrients, resorption of nutrients from senescing leaves proceeded with different kinetics. The maximum nutrient resorption efficiency (the fraction of specific nutrient resorbed from the leaves at the end of leaf fall) did not depend on the mid-seasonal nutrient concentration. Species with earlier leaf fall resorbed leaf nutrients at a faster rate, partly compensating for the earlier leaf fall. Nevertheless, the litter-mass weighted mean nutrient contents in leaf litter were still larger in species with earlier leaf fall, demonstrating an inherent trade-off between early leaf fall and efficient nutrient resorption. This trade-off was most important for N. Losses of the non-mobile nutrients calcium and magnesium were unaffected by the timing of leaf fall. There was large variation in the maximum N resorption efficiency among species. Correlations among leaf chemical variables suggested that the maximum N resorption efficiency decreased with the increasing fraction of cell walls in the leaves, possibly due to a greater fraction of N occluded in cell wall matrix. We conclude that species leaf fall phenology and leaf chemistry modify the timing and quantities of plant nutrient losses, and that more diverse forest stands supporting a spectrum of species with different phenologies and leaf types produce litter with more variable chemical characteristics than monotypic stands.     

河口地区橡胶棒孢霉落叶病发生规律调查

2008-2010年的观察表明,云南河口地区的苗圃地及割胶林橡胶棒孢霉落叶病的发病高峰期在8月以后:降雨量对病情发展有决定性作用;始病期出现早能一定程度地加重病情;还观察到病害主要侵染古铜色和淡绿色前期嫩叶,淡绿后期和老叶很少见有侵害。     

Effects of flooding on leaf dynamics and other seedling responses in flood-tolerant Alnus japonica and flood-intolerant Betula platyphylla var. japonica

Two-year-old seedlings of Alnus japonica Steud. and Betula platyphylla var. japonica Hara were flooded from mid-June to early November, to study the effects of flooding on seedling survival and growth, morphological changes in stems and roots, leaf emergence, leaf fall, and leaf longevity. In A. japonica, growth was not affected by flooding, except for a slight decrease in height growth, but some morphological changes of stems and roots were observed, i.e., stem base hypertrophy, hypertrophied lenticels, formation of adventitious roots and development of new roots. In B. platyphylla var. japonica, growth was severely reduced by flooding and all seedlings died by the 20th week of flooding, without showing any adaptive morphological changes in stems or roots. Flooding induced rapid depression of leaf emergence, promoted leaf abscission, and reduced leaf longevity in B. platyphylla var. japonica. In contrast, in A. japonica, basal leaf senescence was delayed in flooded seedlings, thereby extending leaf longevity compared with unflooded seedlings.     

Diversity of deciduousness and phenological traits of key Indian dry tropical forest trees

? In seasonally dry tropical forests deciduousness (leaflessness) is an important strategy of trees to survive in water stress period during summer. Deciduousness is a reflection of interacted effect of seasonal drought, tree characteristics and soil moisture conditions.

? The present study aims to document the diversity in leaf pheno-phases in terms of duration of deciduousness (which is reciprocal to growing season length), wood density, leaf mass per area (LMA) and leaf strategy index in 24 important tree species growing in the Vindhyan dry tropical forest in India.

? On the basis of phenological observations, the tree species were categorized into two main groups: leaf exchanging species exhibiting overlapping periods of leaf fall and leaf flush, and deciduous species whose timings of leaf flush and leaf fall differ resulting in a time lag (deciduousness) between the completion of leaf fall and initiation of leaf flush. Presence of wide range of deciduousness duration (from ca. a week to 7 months) among dry tropical trees indicates large variations in their growing season length. In the tree species studied, as the duration of deciduousness increased, leaf flushing period decreased significantly but leaf fall period showed little variation.

? Differing deciduousness in tree species exhibited substantial differences in their leafing (vegetative growth) pattern, as reflected by ratio of durations of leaf flush to leaf fall (leaf strategy index). Across different species, duration of deciduousness was significantly positively correlated with leaf strategy index, and significantly negatively correlated with both wood density and LMA.

? Wide variations in deciduousness, leaf strategy index, wood density and LMA in the 24 species investigated indicate considerable functional diversity in tree species growing in Vindhyan dry tropical region. Variation in seasonal duration of deciduousness among species is reflections of differences in tree functional traits like stem wood density, leaf strategy index and LMA.

     

Coarse and fine root respiration in aspen (Populus tremuloides)

Coarse and fine root respiration rates of aspen (Populus tremuloides Michx.) were measured at 5, 15 and 25 degrees C. Coarse roots ranged from 0.65 to 4.45 cm in diameter, whereas fine roots were less than 5 mm in diameter. To discriminate between maintenance and growth respiration, root respiration rates were measured during aboveground growing periods and dormant periods. An additional measurement of coarse root respiration was made during spring leaf flush, to evaluate the effect of mobilization of resources for leaf expansion on root respiration. Fine roots respired at much higher rates than coarse roots, with a mean rate at 15 degrees C of 1290 micromol CO2 m-3 s-1 during the growing period, and 660 micromol CO2 m-3 s-1 during the dormant period. The temperature response of fine root respiration rate was nonlinear: mean Q10 was 3.90 for measurements made at 5-15 degrees C and 2.19 for measurements made at 15-25 degrees C. Coarse root respiration rates measured at 15 degrees C in late fall (dormant season) were higher (370 micromol CO2 m-3 s-1) than rates from roots collected at leaf flush and early summer (200 micromol CO2 m-3 s-1). The higher respiration rates in late fall, which were accompanied by decreased total nonstructural carbohydrate (TNC) concentrations, suggest that respiration rates in late fall included growth expenditures, reflecting recent radial growth. Neither bud flush nor shoot growth of the trees caused an increase in coarse root respiration or a decrease in TNC concentrations, suggesting a limited role of coarse roots as reserve storage organs for spring shoot growth, and a lack of synchronization between above- and belowground growth. Pooling the data from the coarse and fine roots showed a positive correlation between nitrogen concentration and respiration rate.     

4种药剂防治美国山核桃黑斑病林间药效试验

为有效防治美国山核桃黑斑病的发生,2017年在浙江省建德市美国山核桃Carya illinoensis林病害始发期和盛发期通过林间试验比较了75%肟菌·戊唑醇水分散粒剂4 000倍液、苯甲·嘧菌脂悬浮剂1 500倍液、苯甲·丙环唑乳油2000倍液、80%代森锰锌可湿性粉剂400倍液4种不同杀菌剂对美国山核桃黑斑病病原菌小孢拟盘多毛孢Pestalotiopsis microspore的防治试验。结果表明:除80%代森锰锌可湿性粉剂(保护性杀菌剂)400倍液防治效果略差外,其他3种杀菌剂(治疗性杀菌剂)对美国山核桃叶片和果实黑斑病均有较好的防治效果,落叶期推迟时间和产量增量均显著高于对照组。其中施用75%肟菌·戊唑醇水分散粒剂4 000倍液对美国山核桃病叶、病果防治效果最好,分别为97.06%和98.16%;落叶期推迟时间最长,比对照推迟98 d;产量增加最大,为对照的362.86%;其次为苯甲·嘧菌脂悬浮剂1 500倍液。研究结果表明,75%肟菌·戊唑醇水分散粒剂4 000倍液、苯甲·嘧菌脂悬浮剂1 500倍液、苯甲·丙环唑乳油2 000倍液3种治疗性防治药剂能有效防治美国山核桃黑斑病。     

橡胶树棒孢霉落叶病与炭疽病苗圃同防药剂筛选

4种农药对橡胶树棒孢霉落叶病和炭疽病的苗圃防效试验结果:参试农药对棒孢霉落叶病和炭疽病都有不同程度的防效,其中以百菌清最好,防效分别达到80.05%和74.12%,显著高于其它农药处理。     

Enhancement of understory productivity by asynchronous phenology with overstory competitors in a temperate deciduous forest

Some saplings and shrubs growing in the understory of temperate deciduous forests extend their periods of leaf display beyond that of the overstory, resulting in periods when understory radiation, and hence productivity, are not limited by the overstory canopy. To assess the importance of the duration of leaf display on the productivity of understory and overstory trees of deciduous forests in the north eastern United States, we applied the simulation model, BIOME-BGC with climate data for Hubbard Brook Experimental Forest, New Hampshire, USA and mean ecophysiological data for species of deciduous, temperate forests. Extension of the overstory leaf display period increased overstory leaf area index (LAI) by only 3 to 4% and productivity by only 2 to 4%. In contrast, extending the growing season of the understory relative to the overstory by one week in both spring and fall, increased understory LAI by 35% and productivity by 32%. A 2-week extension of the growing period in both spring and fall increased understory LAI by 53% and productivity by 55%.     

柿角斑病（Cercaspora kaki Ell.et Ev.）对日本甜柿的危害及控制

角斑病是日本甜柿的重要病害，严重影响树势，造成早期落叶落果。在浦江，该病原以菌丝体在病叶，病果柿蒂上越科；翌年４月开始侵染，借雨水传播从气孔侵入。采用及时清理病叶，病柿蒂，搞好林内卫生，适时化防等措施，病情可以得到有效控制。     

Leaf-fall phenology along a topography-mediated environmental gradient in a cool–temperate deciduous broad-leaved forest in Japan

Leaf-fall phenology was studied in a cool–temperate deciduous broad-leaved forest in central Japan in relation to the topographic environmental gradients that occur along a short mountain slope. Leaf-fall phenology was described quantitatively using data from leaf litter collected along the slope. In autumn, leaf fall at the study site tended to occur slightly earlier on the upper slope than on the lower slope. This pattern was found at both the stand and the species levels. Our results suggest that leaf-fall phenology may be affected by difference in microclimatic conditions, because environmental conditions are thought to be more severe on the upper slope than on the lower slope. The less intensive methods used in this study, the litter trap method, and Dixon’s model succeeded in quantifying the phenological patterns of leaf fall within stands and within species along the short mountain slope.