水稻赤枯病的发生与防治

针对盘锦地区水稻赤枯病发生情况，对其病害进行研究。介绍了盘锦地区水稻赤枯病的发生时期、症状和发病原因，并从合理施肥、预防根部中毒、选用抗病品种、采取壮秧早播、浅水灌溉等技术措施方面提出了行之有效的预防与防治措施。     

水稻赤枯病的发生与防治

针对盘锦地区水稻赤枯病发生情况,对其病害进行研究。介绍了盘锦地区水稻赤枯病的发生时期、症状和发病原因,并从合理施肥、预防根部中毒、选用抗病品种、采取壮秧早播、浅水灌溉等技术措施方面提出了行之有效的预防与防治措施。     

水稻生理性赤枯病发病原因分析及防治措施

2005年,黑龙江省八五八农场大面积发生水稻赤枯病,对发病田的调查发现,土壤缺锌、土壤环境条件恶化（如低洼冷浸田）、秸秆还田后长期深水灌溉等是诱使当地赤枯病发生的主要原因.其防治措施主要是改进耕作技术、改革水层管理和科学施肥等.     

芦笋茎枯病的发生和防治

本文阐述了芦笋茎枯病发生的症状、病原菌、侵染循环及引发茎枯发生的气候条件与栽培条件因素，并提出了综合防治的措施，有效地控制了茎枯病的发生与蔓延。     

棉花红叶茎枯病的发生与防治

棉花红叶茎枯病为生理性病害。近年来 ,随着产量的提高 ,土壤中供肥结构都有不同程度的发生。发病的棉株 ,上部座不住桃 ,中部桃子小 ,整个棉株吐絮不畅 ,造成大幅度减产。棉株一般从主枝或侧枝顶端叶片开始发病 ,自上而下 ,由外向内失绿 ,失绿部分由紫红变成暗红色 ,后期全叶红褐色 ,叶片发脆 ,叶边翻卷 ,逐渐变褐 ,焦枯 ,叶柄失水干枯 ,引起大量落叶 ,形成茎枯死亡。引起棉花红叶茎枯病的主要原因是干旱 ,其次肥水不足 ,特别是缺钾田块 ,造成营养失调 ,更易发病。另外 ,花期阴雨天多 ,田间积水 ,有机肥缺乏 ,沙碱性过重 ,重茬田均易引发此…     

番茄芽枯病现状调查及其防治

针对番茄芽枯病发生现状,在阐述该病害表现症状的基础上,分析了其发病特点及原因,包括水分供应不足、高温引起水分失衡、高温烫伤及微量元素不足等,并从培养无病壮苗、定植管理、水分管理、蹲苗及中午通风遮阳等方面论述了番茄芽枯病的防治方法.     

水改旱新棉区茎枯病和叶病的发生与防治

棉花茎枯病是棉花苗蕾期常见病害之一。其初侵染源以种子带菌为主,棉苗出土后至现蕾期都有利于其发生、扩展、蔓延。江西省彭泽县杨梓乡1991年是水改旱新棉区,茎枯病、叶病在局部棉地有所发生。对此,我们进行调查研究,并采取了一定措施。现将其发生特点及防治技术简述如下。     

南疆地区棉花红叶枯病的研究

棉花红叶枯病是一种生理性病害。研究结果表明,氮素营养缺乏引起体内代谢平衡失调,是红叶枯病发生的主要生理原因。红叶枯病与棉花缺钾症不同,它的发生不一定是由于缺钾所引起的。影响红叶枯病发生的各种环境因素中,低温阴雨天气可能是南疆棉区诱发此病的一个重要因素。     

水稻鞘腐病的发生与防治技术

介绍了水稻鞘腐病的发病症状,阐明了该病的病源及侵染循环,指出了该病的发病条件,并从选用抗病品种、消灭菌源、加强水肥管理等环节详述了防治技术。     

关于噬菌体在防治水稻白叶枯病上的研究

培育抗白叶枯病菌的水稻品种,是公认的防治水稻白叶病的一条有效途径。但由于水稻抗性基因单一,容易导致对该病抗性的脆弱;化学防治方法的效果不理想。且易造成环境污染。因此。急需探索一条有效、安全、廉价的新途径。本研究从生物防治的角度出发,建立了一套新的技术体系。利用噬菌体来防治水稻白叶枯病。结果显示。特殊的病原噬菌体能够显著地降低水稻白叶枯病的发病率。     

旱稻病虫草鼠发生与防治技术初报

一、概况干旱缺水是我国水稻生产面临的最大威胁 ,也是制约我国稻作面积扩大和产量提高的重要因素。旱稻是一种抗旱性极强的栽培稻类型 ,可在节约７０%用水的情况下取得与栽培稻相似的产量 ,应用旱稻实现水稻旱作对于节约水资源、增加粮食产量、减少能源消耗、保护生态环境具有重要意义。试验表明 :旱稻适合在干旱条件及无灌溉设施的靠天田、坡耕地上种植 ,由于旱稻的根系长且发达 ,保土效果良好 ,旱稻种植地块的土壤侵蚀与全园植草地块土壤侵蚀量相近 ,其单位面积流失量仅为６７．７７ｔ／ｋｍ２ ,比无植被覆盖的幼林果园地减少７５．８%。…     

Interrelations between nitrogen and phosphorus fertilization and early blight control of potatoes

Three different rates of soil-applied nitrogen were combined in all possible combinations with different schedules of fungicidal sprays for early blight (Alternaria solani) control in field experiments for three consecutive years. The nitrogen was applied with a constant rate of phosphorus. Yield response to fungicidal sprays was more pronounced when potato plants had received nitrogen and phosphorus. Both spraying and fertilizer application reduced the percentage of leaflets infected by early blight. However, the effect of the fungicide was greater than that of fertilizers. Estimates based on the cost and price assumptions indicated that $1.00 investment in the optimum number of fungicidal sprays at the adequate rate of fertilizer returned $8.34, $9.71 and $1.89 in 1970, 1971 and 1972, respectively.     

The critical period for control of early blight (Alternaria solani) of potato

The purpose of this study was to identify when the critical period for control of early blight occurs and thus the need to initiate a spray schedule of protectant fungicides. The initiation of weekly fungicide spray schedules was staggered to identify the critical period. The accumulation of 400 P-Days, environmental conditions favorable for sporulation, spore dissemination and plant infection and airborne spores ofA. solani were detected prior to the critical period each year. Since early blight is a disease of old plants, host susceptibility appeared to be involved in the timing of the critical period in addition to favorable weather and the presence of the pathogen. A measure of potato plant development, and therefore susceptibility toA. solani, is needed to adequately predict the critical period. The accumulation of 400 P-Days may aid in the prediction of the critical period by estimating the time of plant susceptibility and therefore the timing of the first necessary fungicide spray.     

Chemical control of potato early blight and its effect on potato yield

Potato early blight infection was reduced significantly by Daconil 2787, Difolatan and Manzate D. Rates of 0.50 1b/A to 1.5 1b/A were effective until inoculum loads increased as the season progressed then the higher rates were significantly more effective than the lower ones. Consistent yield increases in the range of 18 to 39% were demonstrated when early blight was controlled. Statistically significant yield increases were shown in seasons when severe Verticillium wilt or early killing frosts did not shorten the growing season and negate the beneficial effects of early blight control.     

Estimating potato yield responses from chemical control of early blight in Minnesota

The effect of early blight on tuber yield of two potato (Solanum tuberosum L.) cultivars (Russet Burbank and Norland) was evaluated using number and timing of applications of three chemicals to generate different disease epidemics in 1981 and 1982. Under the non-irrigated farming conditions in Minnesota, there were no significant differences among captafol, triphenyltin hydroxide and maneb-Zn in blight control to increase yield. Of the five spray schedules tested, a 7–10 day spray schedule initiated when blight severity exceeded 0.01%, and a 7–10 day schedule initiated when blight was found above the lower third of the plant, generally gave significant, positive yield responses with all three chemicals. At Rosemount in 1982, the greatest yield increases (relative to unsprayed) obtained were 34.9% and 48.6% in total tuber yields for Norland and Russet Burbank, respectively. At Rosemount in 1982, the highest yield increases (relative to unsprayed) obtained were 92.2% and 56.6% in total tuber yields for Norland and Russet Burbank respectively. At Grand Forks in 1981, the highest yield increases were 126.8% and 34.6% in total tuber yields for Norland and Russet Burbank respectively. Across all three experiments, maximum yield losses (percentage of [[yield of ‘healthy’—yield of unsprayed check]/yield of ‘healthy’’]) were 58.4% (US #1 tubers) and 55.9% (total tubers) for cv. Norland and 34.4% (US #1 tubers) and 36.2% (total tubers) for cv. Russet Burbank.     

Influence of potato cultivars on the effectiveness of fungicide control of early blight

Three potato cultivars differing in degree of susceptibility to early blight were grown under crop management practices typical for Pennsylvania in 1987 and 1988. There were three experimental treatments: no fungicides, mancozeb with weekly applications initiated at 7 or 8 weeks after planting (early treatment), and weekly applications initiated at first symptoms of disease (late treatment). The no-fungicide control treatment had significantly higher AUDPC values than either treatment with fungicides and the no-fungicide treatment had significantly lower yield in 1987 but not in 1988. Tubers from the no-fungicide control had lower specific gravity. Norchip, the cultivar most susceptible to early blight examined in this study, responded the most in yield increases by the increased fungicide applications.     

Effects of rice-water chestnut intercropping on rice sheath blight and rice blast diseases

Both sheath blight and blast are important rice diseases worldwide. The exploration of environmentally sound practices to control these diseases will help to reduce fungicide application. Effects of rice (Oryza sativa) intercropping with water chestnut (Eleocharis dulcis) on rice sheath blight and rice blast disease as well as the extracts of different plant parts and root exudates from water chestnut on pathogens of rice sheath blight (Rhizoctonia solani) and rice blast disease (Magnaporthe oryzae) were investigated using pot experiments and bioassay tests. The results from pot tests showed that rice-water chestnut intercropping system suppressed sheath blight and blast and improved land equivalent ratio (LER). The results from bioassay tests indicated that extracts and root exudates from water chestnut had significant effects to inhibit the expansion of these pathogens. The scales of these inhibitions were time and concentration dependent. The antifungal activities of the extracts from aboveground parts and pulp of water chestnut were significantly higher than the extracts from other parts and root exudates. The water extracts of aboveground parts showed the highest antifungal activity on both pathogens according to EC₅₀ values. The antifungal activities of the same extracts from water chestnut on R. solani were significantly higher than on M. oryzae. The result suggests that water chestnut possesses bioactive substances to suppress rice sheath blight disease and rice blast disease. The rice-water chestnut intercropping system can be used as an environment-friendly method for diseases control in rice field.     

Evaluation of sprinkler application of fungicides for control of potato early blight in Colorado

Sprinkler application of four fungicides, Du-Ter 47.5% W.P. (0.70 kg/ha), Difolatan 4F (3.51 1/ha), Bravo W-75 (1.68 kg/ha) and Bravo 500 (1.17 1/ha, 1.761/ha and 2.341/ha) were evaluated in Colorado for control of potato early blight caused byAlternaria solani (Ellis & G. Martin) L.R. Jones and Grout and compared to the conventional method of airplane application. Fungicides applied through center pivot irrigation systems generally achieved disease control equal to airplane application. Application of fungicides through both center pivot sprinklers and by airplane effectively reduced early blight infection. Control of early blight by airplane or sprinkler application of fungicides significantly (P = 0.05) increased potato yields in 1978. In other years (1977, 1979 and 1980) fungicide applications which reduced disease severity generally increased tuber yields but the increases were not significant when compared to the control.