Testing variability in pathogenicity ofPhytophthora cactorum, P. citrophthora andP. syringae to apple, pear, peach, cherry and plum rootstocks

The relative virulence ofPhytophthora cactorum andP. syringae originating from almond trees, and ofP. citrophthora originating from citrus, to apple, pear, peach, cherry and plum rootstocks, was studiedin vivo andin vitro. Results of the different experiments were in good agreement. All testedPhytophthora isolates showed little virulence to pear rootstocks-causing only minor crown rot symptoms - and no virulence at all to apple rootstocks. In contrast, they were highly virulent to stone fruit rootstocks, causing crown rot disease. The non-pathogenicity of these isolates to pome rootstocks could be interpreted as strict host specificity.     

山东苹果主要病虫害化学防治技术

山东省苹果园害虫优势种群是蚜虫、桃小食心虫、苹小卷、金纹细蛾、害螨等 ;病害主要是斑点落叶病、轮纹病。根据不同病虫害的发生发展规律和烟台农科院多年来的化学防治试验研究 ,明确了不同苹果品种上适用的有效药剂和不同药剂的杀虫 (菌 )谱、用药适期、施药方法 ,制定了相应的防治策略 ,提出了合理用药、交替施药和安全喷药等诸多注意事项     

RAPD及其在果树上的应用

就RAPD的特点、操作及其在果树品种鉴定、遗传多样性检测、系谱解析和遗传图谱构建等方面的应用和进展进行了简要的阐述。     

天津市设施果树发展对策探讨

介绍了天津市果树设施栽培的现状及存在问题,分析了发展设施果树的必要性,并提出了今后天津市果树设施栽培的发展方向。     

浅谈海口市古树名木的资源特征及其保护

总结分析了海口市古树名木资源的种类构成、树龄结构、生长分布环境状况以及有关价值作用,并就当前海口市古树名木管理与保护中存在的问题进行分析,提出合理保护开发古树名木资源的几点建议。     

劈破法扦插育苗试验研究

将仿照古代的劈破法与现今常用的马耳型剪法扦插育苗进行对比,证明劈破法扦插育苗有提高扦插成活率和促进多生根以及加快主梢高生长的效果,值得推广应用。     

杨凌地区柳树行道树蛀干害虫危害及防治

本文通过对杨凌示范区城市园林绿化树种蛀干害虫危害现状及防治措施的调查,揭示当前关中地区城市园林蛀干害虫发生特点及主要应对策略,为城市园林中控制蛀干害虫扩散、危害提供决策依据。     

午潮山常绿阔叶林气候生态效应定位研究

午潮山常绿阔叶林气候生态效应，经过８年（１９８８￣１９９５）定位观测研究，取得了若干规律性数据，加深了对常绿阔叶林生态系统气候生态学特征的认识，为持续经营、保护、利用和发展常绿阔叶林，提供了一定的科学依据。文中较系统地论述了午潮山常绿阔叶林的日照、温度、湿度，林内降水量再分配，酸雨等问题。     

老岭自然保护区的野生果树种质资源

青龙县老岭的野生果树种质资源比较丰富，初步查明有１２种，５０种。简要叙述了主要种的生物学特点及用途，进行了必要的讨论。     

Changes on carbohydrates and nitrogen content in the bark tissues induced by artificial chilling and its relationship with dormancy bud break in Prunus sp.

Stem cuttings of peach, nectarine, plum and apricot, obtained from 1-year-old shoots at leaf drop in autumn, were exposed at a constant 3.0 ± 0.1 °C to simulate different chilling accumulation treatments (0, 500, and 1000 chilling hours). A set of 10 excised shoots was forced to budbreak after chilling accumulation; a second set of 10 excised shoots was used to analyse sugars, starch, and ammonium-, nitric- and proteinaceous-nitrogen content in the bark tissues. Sorbitol, fructose and glucose were the main sugars in the bark tissues, whereas sucrose and rafinose showed the lowest quantities in all Prunus sp. studied. Sorbitol and starch concentration decreased whereas glucose and fructose concentration increased with chilling. Ammonium-nitrogen showed the more dramatic increase with medium chilling treatment, decreasing again at high chilling exposure. No modifications in proteinaceous- and nitric-nitrogen levels were observed due to chilling. Chilling treatments increasing flowering intensity showed high ammonium- and proteinaceous-nitrogen content in the bark tissues of the stem cuttings, whereas those reducing flowering intensity showed high starch and nitric-nitrogen content, in three of the four Prunus sp. studied. Ammonium-nitrogen content gives the highest correlation with flowering intensity.