Effects of temperature and concentration of the accelerators ethoxylated alcohols,diethyl suberate and tributyl phosphate on the mobility of [14C]2,4‐dichlorophenoxy butyric acid in plant cuticles

Intrinsic activities of monodisperse ethoxylated dodecanols (MEDs), diethyl suberate (DESU) and tributyl phosphate (TBP) were investigated using Stephanotis floribunda leaf cuticular membranes (CMs) and [¹⁴C]2,4‐dichlorophenoxy butyric acid (2,4‐DB) as a model solute. When sorbed in cuticular membranes, MEDs, DESU and TBP increase solute mobility and are called accelerators for this reason. With MEDs, dose‐effect curves (log mobility vs accelerator concentration) were linear but, with DESU and TBP, curves convex to the x axes were obtained that approached a maximum at 90 and 150 g kg⁻¹, respectively. Accelerators increased the mobility of 2,4‐DB in the CMs by 9‐ to 48‐fold, and effects were larger at lower temperatures (range 15–30 °C). Activation energy for diffusion of 2,4‐DB was 105 kJ mol⁻¹, decreasing with increasing accelerator concentrations to 26 kJ mol⁻¹ with DESU at 90 g kg⁻¹ and 64 kJ mol⁻¹ with TBP at 150 g kg⁻¹. Thus, the intrinsic activity of DESU was much higher than that of TBP, which implies that, for a given effect, less DESU than TBP would be needed. MEDs were also very effective accelerators, lowering activation energies to 36 kJ mol⁻¹. Data are discussed in relation to increasing rates of foliar penetration of active ingredients at low temperatures. © 2001 Society of Chemical Industry     

Finite dose diffusion studies: II. Effect of concentration and pH on NAA penetration through isolated tomato fruit cuticles

The effects of NAA [2‐(1‐naphthyl)acetic acid] concentration and pH on penetration of NAA from aqueous droplets (5 µl) through isolated tomato (Lycopersicon esculentum) fruit cuticles were studied using a finite dose diffusion system. Penetration time‐courses were characterized by a lag phase, which generally extended beyond the time of droplet drying. Initially penetration rates increased, reached a maximum penetration rate, remained constant for several hours, and then decreased with time. Penetration approached a plateau within 120 h after droplet application. Increasing NAA concentration in the donor droplet increased NAA penetration in both the presence and absence of the citric acid buffer (20 mM , pH 3.2). Maximum rates of penetration and the total amount of NAA that penetrated at 120 h were both linearly related to the initial concentration of the donor droplet (ranging from 0.001 to 0.1 mM NAA). The apparent first‐order rate constants for the concentration dependence of NAA penetration rates were greater with buffer than without (0.94 × 10⁻⁸ vs 0.50 × 10⁻⁸ m s⁻¹, respectively). While pH of the receiver solution (pH 6.2 vs 2.2) did not affect penetration, decreasing donor pH from 6.2 to 2.2 increased NAA penetration at 120 h. © 2000 Society of Chemical Industry     

不同杀菌剂对莲藕腐败病菌的室内毒力测定及田间防治效果

人工室内接种筛选出F1和F2两个莲藕腐败病菌强致病性菌株。应用菌丝体生长速率法,测定了生产中防治莲藕腐败病常用化学农药对F1和F2的室内毒力。测定结果表明,供试药剂对该病原菌菌丝生长的抑制作用存在较大的差异,其中以硫磺多菌灵的效果最好,对2个供试菌株的EC50分别为11.22μg/mL和12.30μg/mL;其次为甲基硫菌灵,对2个菌株的EC50分别为46.06μg/mL和11.32μg/mL;腐霉利的效果最差,对2个菌株的毒力分别为303.09μg/mL和426.12μg/mL。应用室内抑菌效果较好的硫磺多菌灵和甲基硫菌灵对腐败病严重发生的藕田进行病害防治,结果显示,2种药剂对病情的发展具有一定的控制作用。     

Application of fungicides to foliage through overhead sprinkler irrigation – a review

Articles on chemigation with fungicides targeting foliage have been reviewed. They included 23 fungicides tested on 10 crops. Many studies compared chemigation to a check treatment, while others also included conventional methods. Chlorothalonil, followed by mancozeb, fentin hydroxide and captafol were the most studied fungicides, while peanut (Arachis hypogaea), potato (Solanum tuberosum), tomato (Lycopersicon esculentum ), and dry beans (Phaseolus vulgaris) were the most studied crops. Center pivot, followed by solid set, were the irrigation systems most frequently used. The minimum volume of water applied by some center pivots (25 000 litre ha⁻¹ ) is 25 times the maximum volume of water used by conventional ground sprayers. The reduction of fungicide residue on foliage caused by the very large volume of water used by chemigation might be offset by the following factors: (1) fungicide application at the time of maximum leaf wetness when fungi are most active, (2) complete coverage of plants, (3) reducing greatly the inoculum on plant and soil surface, (4) better control of some soil pathogens, and (5) more uniform distribution of fungicides by center pivot. Furthermore, chemigation avoids mechanical damage and soil compaction. Additionally, some systemic fungicides seem to be absorbed rapidly by the leaves, by root uptake from the soil, or by both. In general, all fungicides applied through irrigation water can lessen disease severity. However, when compared to conventional methods, chemigation with fungicides can be less, equally or more effective depending on crop, pathogen, disease severity, fungicide and volume of water. For Cercosporidium personatum control on peanuts, application of protectant fungicides through irrigation water is less effective than conventional methods, but the results with some systemic fungicides mixed with non-emulsified oil and applied through a relatively low volume of water (2.5 mm) are encouraging. Important diseases of potato and tomato can be controlled nearly as well by chemigation as by conventional methods without impairing yield. The main advantage of chemigation for these crops is avoiding a large number of tractor trips through the field and reduced costs of fungicide application. Chemigation has also been shown to be a good option for control of white mold [ Sclerotinia sclerotiorum] on dry beans. © 1999 Society of Chemical Industry     

青风藤叶枯病病原菌的分离鉴定及防治药剂的筛选

2021年春季,从湖南省怀化市中方县正清制药青风藤基地和湖南农业大学试验基地分别采集青风藤叶枯病病叶,利用组织分离法获得病原菌,并进行柯赫氏法则验证。借助形态学鉴定和分子系统学分析,明确青风藤叶枯病病原为交链隔孢(Alternaria alternata)。利用菌丝生长速率法对5种药剂(95%苯醚甲环唑、98%咪鲜胺、96%己唑醇、96.5%丙硫菌唑、98%嘧菌酯)进行筛选,结果显示95%苯醚甲环唑抑菌效果最好,EC₅₀为0.043 6 mg/L;98%嘧菌酯抑菌效果最差,EC₅₀值为8.447 3 mg/L。     

狗牙根平脐蠕孢菌生物学特性及药剂筛选

 对狗牙根平脐蠕孢菌的生物学特性及5种杀菌剂对该病原菌的抑制作用进行了研究。结果表明：狗牙根平脐蠕孢菌对多种碳、氮源都能利用,以蔗糖和硝酸钾、L-天冬酰胺最好,但以脲为氮源的培养基生长较差。菌丝最佳生长温度是25~30 ℃之间，在25 ℃时最利于产孢,菌丝生长和分生孢子的致死温度是56 ℃；该菌在pH 3~11范围内均能生长，产生分生孢子，菌丝生长的最适pH 5~7，产孢量最大的pH是 3，9，10；糖浓度在2%~8%菌丝能生长，在糖浓度为2%时菌丝生长最好，产孢量最高；光照对病原菌的菌丝生长和产孢有明显影响,在全光照的条件下有利于菌丝的生长，但不会产孢，黑暗12h光照12h既利于菌丝生长又利于产孢，而全黑暗的条件下不利于菌丝生长和产孢。对5种杀菌剂的研究表明：退菌特和百菌清对狗牙根平脐蠕孢菌菌丝生长的抑制效果较好，其它杀菌剂也能有效的抑制菌丝的生长。     

Preliminary Study of Variable Rate Application – Organic Liquid Fertilizer by Using SPAD Chlorophyll Meter on System of Rice Intensification (SRI) Cultivation

Knowing actual nutrient requirements for rice plants is crucial in supplying the correct amount of fertilizer, especially nitrogen since nitrogen is one of the most key limiting nutrients in rice cultivation. A preliminary study of variable rate application (VRA) on System of Rice Intensification (SRI) planting by using organic foliar fertilizer was carried out to determine the effectiveness of precision fertilization. Foliar fertilizer was formulated based on actual nitrogen needed by rice plants using Soil-Plant Analyses Development (SPAD) chlorophyll meter measurements. The experiment was laid out in a randomized complete block design (RCBD) with four treatments (50% fixed rate, 100% fixed rate, 150% fixed rate and VRA) and four replications for each treatment. Plant growth performances (plant heights, number of tillers, number of panicle and flower) and yield performances (grain yield, number of grain, 1000-grain weight and number of spikelets) were recorded during the study. The results showed that foliar application of VRA resulted in significantly higher yield performances; grain yield (13.65 g), number of grain (807.50), 1000-grain weight (16.79 g), and number of spikelets (7.50) compared to uniform fertilizer applications. VRA treatments had the highest SPAD readings at every planting stage during the experiment; however, a high nitrogen supply was needed during the mid-tillering stages (35 DAT) compared to other fertilizer rates. Besides, VRA application shows the most savings in term of total nitrogen supply (415 µg) compared to uniform rates application; 50% fixed rate (400 µg), 100% fixed rate (810 µg), and 150% fixed rate (1210 µg).     

EFFECT OF FOLIAR APPLICATION OF UREA,MOLYBDENUM, BENZYLADENINE,SUCROSE AND SALICYLIC ACID ON YIELD,NITROGEN METABOLISM OF RADISH PLANTS AND QUALITY OF EDIBLE ROOTS

In 2006–2007 small radish was cultivated in a pot experiment. Foliar applications were applied twice with solutions of the following compounds: 1) control (water); 2) urea; 3) urea+molybdenum (Mo), 4) urea+Mo+benzyladenine (BA); 5) urea+Mo+BA+sucrose; 6) urea+Mo+BA+sucrose+salicylic acid (SA), 7) BA; 8) SA; and 9) sucrose. The above solutions contained following concentrations of compounds: urea 20 g dm^?3, sucrose 10 g dm^?3, Mo 1 mg dm^?3, BA 5 mg dm^?3 and SA 10 mg dm^?3. In comparison with the control, spraying plants with the solution of urea+Mo+BA+sucrose and SA only caused an increase in leaf mass of one plant. Foliar applications did not have any effect on the yield of edible roots. When compared with the control, the use of sucrose resulted in a decreased content of nitrate (V) in leaves, while the application of urea+Mo+BA+sucrose led to elevated content of nitrate (V) in roots. In case of spraying plants with solutions containing urea (combinations no. 2–6) there was a tendency to increase ammonium (NH₄ ⁺) and nitrogen (N)-total content in leaves and roots, and increase in N uptake by leaves and by the whole plant but not by the radish roots. In combinations 7–9 we noted a decline in the level of ascorbic acid, and in combinations 2–6 there was a decrease in the content of soluble sugars in roots. In comparison with the control, an increase was observed in combinations 2 and 3, while in combinations 7–9 a decrease in the content of free amino acids in roots was observed. None of the combinations with foliar application caused any significant changes in the content of assimilative pigments in radish leaves and concentration of nitrate (III), dry matter in leaves and roots, the content of phenolic compounds, content of potassium (K), magnesium (Mg), calcium (Ca) extracted with 2% acetic acid in roots as well as free radical activity of radish roots.     

玉米大斑病发生及防治若干问题的研究

研究了12种化学农药对玉米大斑病菌孢子萌发和菌丝扩展的抑制作用、花粉粒对大斑病菌孢子萌发的影响、离体叶片上病斑的产孢规律等问题。结果表明：代森锰锌及其复配药荆、福美双对大斑病菌孢子萌发、菌丝扩展均有较强的抑制作用;花粉粒对大斑病菌孢子萌发有明显的促进作用;离体叶片上的幼龄病斑仍可旺盛产孢约4d,持续产孢时间可达10d,且在叶片背面病斑产孢量明显高于叶片正面。     

Sensitivity of four Yeasts to Fungicides and CO2 Concentrations and Their Antagonistic Ability in Combination with Fungicide to pathogenic Fungi in vitro

The yeasts Cryptococcus laurentii,Trichosporon pullulans,Rhodotorula glutinis and Trichosporon sp.were used to investigate their sensitivity to four fungicides and different concentrations of CO2,as well as their antagonistic ability to Penicilliumexpansum and Alternaria alternata in vitro when applied with fungicide.There were significant differences in sensitivity to the fungicides among the different yeasts(P = 0.05).R.glutinis was more sensitive to Deccocil,Iprodione and Stroby as compared to other yeasts.Combination antagonistic yeasts with fungicide could more significantly enhance biocontrol ability of the yeasts against the pathogenic fungi in vitro(P = 0.05).C.laurentii was the most effective antagonist among the four yeasts and could completely control spore germination of P.expansum and A.alternata when combined with Stroby at the concentration of 100 μL L-1.The yeasts,except R.glutinis,could grow well on nutrient yeast dextrose agar (NYDA) after 8 d incubation even at 20% CO2 concentration at 25℃.Particularly Trichosporon sp.showeda better adaptability to low temperature as compared to other antagonists.