喷雾助剂对氟啶虫胺腈在富士苹果叶片表面润湿和持留的影响

为明确喷雾助剂在苹果园化学防治中的作用，采用表面张力、接触角和最大稳定持留量等分析了GY-T12、NF-100和迈润等3种喷雾助剂在达到临界胶束浓度 (CMC) 时对22%氟啶虫胺腈悬浮剂药液的表面张力及其在苹果叶片表面润湿性能和持留量的影响。结果显示:当添加的3种喷雾助剂达到其CMC时，氟啶虫胺腈药液表面张力降低至27.64~35.64 mN/m；根据水滴在苹果叶片表面的接触角小于或大于90°判定苹果叶片近轴面为亲水性表面、远轴面为疏水性表面，添加助剂使药液在近轴面和远轴面30 s的静态接触角分别降低23.2°~41.3°和68.0°~93.5°，同时使亲水性近轴面黏附功降低5.36~12.56 mJ/m2，而黏附张力增大9.27~11.26 mN/m，在疏水性远轴面黏附功与黏附张力分别增大27.45~36.66 mJ/m2和47.55~53.28 mN/m，对改善远轴面的黏附润湿性更显著；药液表面张力和最大稳定持留量存在抛物线状函数关系，当表面张力为40.89 mN/m时，持留量达最大值12.53 mg/cm2；3种助剂中，NF-100和GY- T12可显著增加药液持留量，且GY-T12对靶标害虫苹果黄蚜有显著增效作用。本研究结果表明，在苹果园应用时应依据预期目标选择适当的喷雾助剂，并通过调节药液表面张力使其处于适宜范围以增加药液持留量、提高对靶标害虫的毒力。     

几种新型润湿分散剂在悬浮剂加工中的应用评价

为快速表征新型表面活性剂在农药剂型加工中的主要功能,本研究通过测定几类国产高分子表面活性剂的临界胶束浓度及该浓度下的表面张力和润湿时间等性能,初步判断其适合作润湿剂还是分散剂;运用流点法确定了各助剂在多菌灵悬浮剂中的用量及配比;利用不同助剂类型及不同用量加工了多种50%多菌灵悬浮剂,并测定了其性能。结果表明:将润湿剂和分散剂按不同比例混合后,通过测定其流点来确定悬浮剂中助剂用量的方法是可行的;从对各制剂的性能测试结果可以看出,不管是用流点用量还是5倍流点用量,所选助剂多数可成功加工出合格试样。将性能较好的制剂按照农药登记推荐使用浓度稀释1 000倍后,测定其表面张力及在小麦叶片上的接触角和持液量,推断其田间使用情况。结果显示:药液因表面张力过大未能润湿小麦叶片,国产助剂与国外助剂差别不显著,甚至部分国产助剂的性能还优于国外助剂的;制备悬浮剂时将磺酸盐类与聚羧酸盐类分散剂配合使用效果较好。     

嘧霉胺悬浮剂的润湿性能及其靶标表面性质研究

采用光学视频接触角测量仪对加入不同润湿分散剂(7227-A、SOPROPHOR FD和SC-4)的40%嘧霉胺悬浮剂的表面张力及其分量进行了测定,同时研究了作用靶标黄瓜和番茄叶片的表面自由能,以及药液在其上的润湿展布性能。结果显示:不同配方的嘧霉胺悬浮剂其表面张力在39~51 mN/m之间,且均以色散分量为主,其中加入SC-4的药剂表面张力最低(39~48 mN/m);黄瓜和番茄叶片的表面自由能均较小,在22 mJ/m2左右,不利于药液润湿,且以极性分量占主导;各配方药液的水稀释液在番茄叶面上的接触角在51~86°之间,在黄瓜叶面上的接触角在30~62°之间,药液在黄瓜叶面上更易附着,其中加入7227-A的药剂在黄瓜叶片上润湿性能最好,加入SOPROPHOR FD的药剂在番茄叶片上润湿性能最好;田间防治效果与药液的润湿性能呈正相关。表明嘧霉胺悬浮剂对靶标的润湿性能不仅与药液的表面张力有关,也与其分量有关,同时受到靶标表面性质的影响,通过研究药液对靶标润湿性能可分析评价其药效。     

炔草酯微乳剂药液在菵草叶片上的润湿和持留特性分析

为科学使用除草剂防治菵草,采用Zisman图法测定了菵草叶片的临界表面张力及不同浓度炔草酯微乳剂药液的表面张力,利用表面张力法测定了炔草酯微乳剂中表面活性剂的临界胶束浓度及在菵草叶片上的接触角和最大稳定持留量。结果表明,菵草叶片的临界表面张力为31.3 m N/m。炔草酯浓度为676.1 mg/L时,药液表面张力为28.0 m N/m,此时药液中表面活性剂浓度即为临界胶束浓度;浓度为1 000.0、2 000.0 mg/L时,表面活性剂浓度大于临界胶束浓度,其表面张力分别为27.7、27.8 m N/m,接触角均小于60°,润湿性好,最大稳定持留量分别为3.65±0.09、3.83±0.02 mg/cm2,均显著高于其余浓度;其余浓度下表面活性剂浓度均小于临界胶束浓度,药液表面张力大于菵草叶片的临界表面张力(500.0 mg/L除外),接触角介于75.9~125.9°之间,润湿性中等或差,最大稳定持留量相对较低,但均显著高于对照的0.47±0.10 mg/cm2。表明只有药液表面张力小于菵草叶片的临界表面张力,且药液中表面活性剂浓度达到临界胶束浓度时才能使药液在菵草叶片上具有较好的润湿性和较高的最大稳定持留量。     

虫生真菌玫烟色棒束孢PF904表面活性剂的筛选

为筛选适用于玫烟色棒束孢Isaria fumosorosea PF904菌株的表面活性剂,采用OWRK法和表面张力法测定了甘蓝、苹果、茄子和黄瓜叶片的表面自由能以及添加4种表面活性剂后玫烟色棒束孢孢子悬浮液的表面张力和临界胶束浓度(CMC),并采用量角法和重量差值法测定了4种不同植物叶片上的接触角和最大稳定持留量,同时对筛选获得的表面活性剂进行了安全性评价。结果表明:PEG-12聚二甲基硅氧烷(OFX-0193)、ɑ-烯基磺酸钠(AOS)和二异丁基萘磺酸钠(Nekal)3种表面活性剂在125~500 mg/L下均可提高玫烟色棒束孢孢子悬浮液在4种供试植物叶片上的润湿性能;其中250 mg/L的Nekal在甘蓝和苹果叶片上的最大持留量(11.90和13.28 mg/cm^2)和接触角(29.5°和27.5°)均显著优于OFX-0193和AOS,润湿效果最好;在茄子叶片上,添加125 mg/L的OFX-0193时持留量最大(9.45 mg/cm^2);而添加普鲁兰多糖(Pullulan)达到临界胶束浓度时的溶液表面张力大于甘蓝、苹果和茄子叶片的表面自由能,润湿性能最差。孢子萌发抑制率的测定结果表明:添加Nekal和OFX-0193对玫烟色棒束孢PF904的孢子萌发无抑制作用,而AOS则对其表现为抑制作用。因此,在玫烟色棒束孢PF904中添加OFX-0193和Nekal 2种表面活性剂可用于防治苹果、甘蓝类害虫,添加OFX-0193还可用于防治茄类害虫。     

提高吡虫啉悬浮剂在水稻叶面持留量润湿剂筛选

通过测试4种润湿剂水溶液在水稻叶面的初始接触角和最大稳定持有量,筛选出GY-S903和GY-W07作为提高吡虫啉600g/L悬浮剂持留量的喷雾助剂使用。结果表明,GYS903和GY-W07都不同程度的提高吡虫啉600g/L悬浮剂在水稻叶面的持有量,但GY-S903会对水分蒸发后的吡虫啉晶型和粒径产生影响。     

剂型及表面活性剂对农药药液在植物叶片上铺展行为的影响

为研究不同农药剂型及表面活性剂对药液在亲水和疏水植物叶片表面的持留及铺展行为的影响,通过数码显微镜连续摄像的方法,测试了40种药液液滴在棉花(亲水性)和水稻(疏水性)叶片上的持留及铺展行为。选用5%氯虫苯甲酰胺悬浮剂、25%三唑酮可湿性粉剂和20%三唑酮乳油3种不同剂型的农药,以及Silwet 408、NF100和AgroSpred 730 3种不同表面活性剂,配制不同药液,通过注射器产生液滴并用数码显微镜记录液滴在水稻和棉花叶片上的铺展行为。结果表明:农药剂型对药液表面张力影响不显著,但加入不同表面活性剂却对表面张力影响显著,其对降低表面张力影响的显著程度依次为Silwet 408AgroSpred 730NF100;同种表面活性剂对悬浮剂的影响最大,其次是可湿性粉剂,对乳油的影响最小;加入NF100可增加药液液滴在水稻叶片上的持留能力。结合表面张力结果,证明表面张力并非增强药液持留和铺展能力的唯一因素。     

有机硅助剂对10种杀菌剂防治鸡蛋花锈病的增效作用

为评价有机硅助剂对10种杀菌剂防治鸡蛋花锈病的增效作用,以表面张力、扩展直径、最大持留量、田间防效为评价指标,测定添加0.1%有机硅助剂对10种杀菌剂1 000倍液物理性状及田间防效的影响。结果表明,有机硅助剂能显著降低药液表面张力,增大扩展直径,提高药液持留量和防治效果。添加助剂后,药剂表面张力由34.67～66.47 mN/m降低至16.80～22.73 mN/m;扩展直径由2.09～2.56 mm增大至3.49～5.90 mm;持留量由1.43～2.88 mg/cm~2增大至1.94～4.35 mg/cm~2;在相等药剂用量下,有机硅助剂可使杀菌剂田间防效提高16.95%～36.01%。有机硅助剂通过降低药液表面张力,增加扩展直径,提高药液持留量,提高杀菌剂对鸡蛋花锈病的防治效果。     

有机硅助剂对氯虫苯甲酰胺防治稻纵卷叶螟的增效作用研究

为探索有机硅助剂Silwet408对杀虫剂药液理化性能的影响及药液雾滴在稻叶上的行为与对稻纵卷叶螟Cnaphalocrocis medinalis Guenée防效的内在关系,在室内条件下研究了在200 g/L氯虫苯甲酰胺悬浮剂稀释液中添加助剂Silwet408后表面张力、黏度、pH值以及在稻叶上最大持留量的变化,借助OCG法对叶片的表面特性进行表征,围绕叶片倾角分析了单个雾滴在稻叶上的黏附行为,并进行了田间药效试验。结果表明:水稻叶片正、反面表观表面自由能分别为31.48 mJ/m^2和34.19 mJ/m^2;倒二叶和倒三叶的叶角较小,分别为(11.09±2.74)°和(19.98±5.67)°,表明水稻为高倾角叶片形态,不利于雾滴在稻叶上的黏附。200 g/L氯虫苯甲酰胺悬浮剂4000倍和5000倍稀释液的表面张力分别为(44.64±1.04)mN/m和(46.14±0.62)mN/m,均大于稻叶的表观表面自由能,其药液的单个雾滴在79°和70°的倾角稻叶上均呈滚落状态;添加125 mg/L的Silwet408后,药液的表面张力小于稻叶的表观表面自由能,单个雾滴能够黏附在倾角稻叶上并润湿,同时药液在稻叶上的最大持留量也呈极显著增加;200 g/L氯虫苯甲酰胺悬浮剂5000倍稀释液的pH值和黏度在添加Silwet408前后变化不大。田间试验结果表明,添加125 mg/L的Silwet408后,200 g/L氯虫苯甲酰胺悬浮剂5000倍稀释液对稻纵卷叶螟药后14 d的保叶效果和杀虫效果均显著提高。综合研究结果表明,在200 g/L氯虫苯甲酰胺悬浮剂5000倍稀释液中添加125 mg/L的Silwet408可使喷雾药液与水稻植株特性相匹配,进而提高氯虫苯甲酰胺对稻纵卷叶螟的防治效果。     

五种喷雾助剂对240 g/L螺螨酯悬浮剂和15%哒螨灵乳油防治木瓜秀粉蚧的增效作用

为探索喷雾助剂对药液物理性状的影响及防治木瓜秀粉蚧的增效作用,室内条件下研究了添加5种喷雾助剂[芦荟精油、有机硅助剂silwet408、渗透剂JFC-2、氮酮和增效醚(PBO)]对240 g/L螺螨酯悬浮剂和15%哒螨灵乳油表面张力、扩展直径以及最大持留量的影响,并测定了添加喷雾助剂对2种供试药剂防治木瓜秀粉蚧Paracoccus marginatus的增效作用。结果表明:5种助剂均能显著降低药液的表面张力、增大扩展直径并提高药液持留量;室内毒力测定结果表明,5种助剂对240 g/L螺螨酯悬浮剂和15%哒螨灵乳油的毒力具有不同程度的增效作用,增效比分别达5.1%～26.1%和22.7%～41.8%,其中JFC-2和PBO的增效作用较为明显。田间试验结果表明,JFC-2和PBO可提高2种供试药液对木瓜秀粉蚧的田间防效,尤其对高浓度药液的增效作用更为明显,其中JFC-2对240 g/L螺螨酯悬浮剂防效的增效比在10.3%～24.6%之间,增效醚对15%哒螨灵乳油防效的增效比在12.1%～28.9%之间。     

微生物表面活性物质研究进展

微生物表面活性物质是由微生物产生的具有高表面活性的生物分子,环境相容性好,易生物降解,广泛应用于各领域。从微生物表面活性物质生产菌种、化学结构类型和特点、主要生产方法及其在病虫害防治、农药生产加工、土壤改良等领域的应用进展进行了总结和评述,并展望了其未来的发展方向。     

Effects of surfactants on primisulfuron activity in barnyardgrass (Echinochloa crus-galli [L.] Beauv.) and green foxtail (Setaria viridis [L.] Beauv.)

Laboratory and greenhouse studies were conducted to measure the contact angle of primisulfuron droplets with and without surfactants on the leaf surfaces of barnyardgrass and green foxtail, to determine the primisulfuron activity on these weed species, and to examine the spray deposit of primisulfuron with and without surfactants on the leaf surface of green foxtail using scanning electron microscopy. A non-ionic surfactant (NIS) and an organosilicone wetting agent (OWA) were used. The contact angles of 1 μL droplets were measured on the leaf surface using a goniometer. The activity of primisulfuron on barnyardgrass and green foxtail was assessed at 3 weeks after treatment based on visual injury and the fresh weight. The contact angles of the droplets of primisulfuron on the adaxial surface of the barnyardgrass and green foxtail leaves were 152° and 127°, respectively, when applied without surfactant. The addition of either surfactant markedly reduced the contact angle for both weed species, which was lowest when the OWA was added to primisulfuron. The percentage injury of barnyardgrass was very low, even at the higher rate of primisulfuron, regardless of the surfactant. Primisulfuron at 40 g ha⁻¹ controlled 43% of green foxtail without surfactant, which increased to 65% with the NIS and 83% with the OWA. Primisulfuron with a surfactant markedly reduced the fresh weight of green foxtail compared with primisulfuron applied alone, regardless of the primisulfuron rate and surfactant type. The scanning electron micrographs showed a uniform deposit of spray droplets, with close contact of the droplets to the leaf epicuticular surface in green foxtail in the presence of a surfactant compared with no surfactant. The enhanced primisulfuron activity on green foxtail with surfactants was related to the reduced contact angle and uniform deposition of the primisulfuron spray droplets on the leaf surface.     

Cuticular sorption and desorption of a nonionic diethylene glycol monooleate surfactant

Sorption and desorption of ‘Pegosperse’ 100-O(PEG 100-O; diethylene glycol monooleate, containing 15% diester) surfactant by unaltered (CM) and dewaxed (DCM) adaxial cuticle membranes isolated from apple (Malus pumila M.) leaves were studied. The aim of this study was to understand interactions between surfactants and cuticles. Enzymatically isolated cuticles were soaked in buffer or PEG 100-O solution (pH 7–0). and the weight changes of cuticles were measured to determine the amount of surfactant sorbed or desorbed by the cuticles. For very low surfactant concentrations, sorption was measured by changes in the surface tension of the solutions. PEG 100-O sorption by both the CMs and the DCMs occurred mainly in the first three hours and was concentration-dependent. The DCMs always sorbed more surfactant than the CMs. Desorption of PEG 100-O from both CMs and DCMs was rapid in the first few hours and then decreased to a relatively low rate until the surfactant was totally desorbed from the cuticles after about two months. The sorption and complete desorption of the surfactant by both CMs and DCMs show that PEG 100-O interacts with both cutins and waxes of the cuticles and the interactions are reversible.     

Surfactant-enhanced foliar uptake of some organic compounds: Interactions with two model polyoxyethylene aliphatic alcohols

Interactions occurring during the surfactant-enhanced foliar uptake of seven model organic compounds were examined using two homogeneous surfactants, hexaethylene glycol monotridecyl ether (C13E6) and hexadecaethylene glycol monododecyl ether (C12E16). Surfactant–compound and compound–surfactant interactions were detected by measurement of their relative uptake rates following application of c. 0·2 μl droplets of the corresponding radiolabelled formulations. The magnitude of surfactant–compound interaction was found to vary according to the physicochemical properties of both the compound and the surfactant, and was influenced by surfactant concentration and target plant species. Interactive and non-interactive mechanisms, both leading to substantial enhancement of compound uptake, could be identified, but their precise nature could not be elucidated. Although penetration of C13E6 into the site of application appeared to be essential in order to activate the uptake of a compound, substantial absorption of C12E16 was not always required to produce the same effect. The results are discussed in the light of possible sites and modes of action for activator polyoxyethylene surfactant adjuvants.     

Factors affecting the foliar absorption and redistribution of pesticides. 1. Properties of leaf surfaces and their interactions with spray droplets

Foliar uptake into eleven plant species, grown under controlled environment, has been determined for spray deposits of glyphosate, 2, 4-D and prochloraz applied as solutions in aqueous solvents in the presence and absence of an ethoxylated nonylphenol surfactant. Over 24 h, uptake of glyphosate did not exceed 6% of applied chemical into any species whereas uptake of 2, 4-D and prochloraz differed between species and was modified significantly by the addition of surfactant. Uptake of prochloraz was increased consistently by adding surfactant, but the response of 2, 4-D was variable. Increased uptake was attributed mainly to surfactant-enhanced wetting of the leaf surfaces. Uptake of prochloraz per unit wetted area increased in the presence of surfactant but that of 2, 4-D decreased. Uptake of either chemical did not correlate with the presence of specialised leaf surface structures, cuticular morphology or distribution of the chemicals within the dried deposits. The dried chemicals were distributed either uniformly or as annuli as a result of complex interactions between the active ingredient, surfactant and the leaf surfaces. Regression analysis indicated that the epicuticular wax and cuticular membrane were the major sinks for both 2, 4-D and prochloraz during the 24-h period.     

Effects of two surfactant series on the absorption and translocation of 14C-glyphosate in sicklepod and prickly sida

The weed species, prickly sida (Sida spinosa L.) and sicklepod (Senna obtusifolia L.), were treated with ¹⁴C-glyphosate alone and formulated with different polyethlylane oxide (PEO) surfactants in tallow amine ethoxylate and non-ionic alkoxylate series to determine the amount of ¹⁴C-glyphosate absorption and translocation. The surface tension, contact angle, and ¹⁴C-glyphosate distribution were significantly affected by both the presence of different waxes on the plants and by the addition of surfactants to the glyphosate. The surface and contact angle values of the surfactants, with and without glyphosate, showed a significant increase as the PEO number increased in both surfactant series. A higher absorption of the ¹⁴C-glyphosate was recorded for S. spinosa compared with S. obtusifolia. The absorption and translocation of the ¹⁴C-glyphosate increased with the increase in the PEO number of tallow amine ethoxylate. In the case of the non-ionic alkoxylate surfactant series, an increase in the absorption of ¹⁴C-glyphosate was recorded when the surface tension and contact angle values decreased. There was no significant difference in the translocation values obtained in the two species after the addition of the surfactants. The amount of ¹⁴C-glyphosate absorbed by the treated leaf was significantly higher in the case of S. spinosa compared with S. obtusifolia. A linear relationship was observed with the physical properties, ¹⁴C absorption, and the efficacy of glyphosate with the addition of the non-ionic alkoxylate surfactant series. The percentage control was higher with the higher PEO surfactant in the tallow amine ethoxylate surfactant series and with the lower PEO surfactant in the non-ionic alkoxylate surfactant series as the two series are chemically different.     

Selectivity factors relative to asulam for Senecio jacobaea L. control in Medicago sativa L. I. Retention,uptake and translocation*

Senecio jacobaea L. and Medicago sativa L. plants grown in a glasshouse were treated with foliar applications of aqueous solutions of asulam. Retention on foliage, uptake and translocation were measured in both species. Retention was greater in S. jacobaea than in M. sativa when no surfactant was added and similar when surfactant was added. Addition of surfactant modified spray distribution and increased asulam uptake in M. saliva but did not in S. jacobaea. S. jacobaea translocated over twice as much asulam from the treated area as M. sativa. These data suggest that surfactant should not be added for maximum selectivity. Differences in species response to asulam treatments are partially, but not entirely, explained by differences in retention, uptake and translocation.     

Enhanced soil sorption of methidathion using sewage sludge and surfactants

Batch experiments were carried out to examine the partitioning of an organophosphorus insecticide, methidathion, in non-amended agricultural soil and soil amended with urban sewage sludge and/or different types of surfactant. Kinetic data showed that sewage sludge significantly reduced adsorption rate, whereas amendment of the soil with the cationic surfactant tetradecyltrimethylammonium bromide (TDTMA) at 10 x CMC (critical micellar concentration) increased the adsorption rate by a factor of 10. The adsorption isotherms were evaluated using the Freundlich model. The soil adsorption capacity for methidathion was enhanced by amendment with sewage sludge and even more significantly with TDTMA at 10 x CMC or combined with sewage sludge. TDTMA conferred a high hydrophobic character to the soil, enhancing the adsorption capacity of the rather hydrophobic methidathion. The amendment of soil both with sewage sludge and TDTMA combines the increased hydrophobicity with a higher surfactant retention by organic matter, due to an increase in cation exchange capacity, which promotes even more the adsorption capacity for the insecticide. An anionic surfactant, linear alkylbenzene sulfonate, and the non-ionic Tween 80 only induced a slight modification in the kinetics and adsorption of methidathion.     

Biocontrol efficacy of Colletotrichum truncatum for hemp sesbania (Sesbania exaltata) is enhanced with unrefined corn oil and surfactant

In greenhouse and field experiments, an oil-in-water emulsion of unrefined corn oil and Silwet L-77 increased the biological weed control efficacy of Colletotrichum truncatum (Schw.) Andrus et Moore for control of the weed, hemp sesbania ( Sesbania exaltata [Raf.] Rydb. ex A.W. Hill). The surfactant – corn oil emulsion stimulated germination and appressoria formation in vivo and in vitro and delayed the need for dew. We hypothesize that the corn oil protected the conidia from desiccation during the dew-free period and the surfactant stimulated spore germination and appressoria formation. In field experiments conducted over 3 years, a single application of a 50% (v/v) unrefined corn oil tank mixture containing 0.2% (v/v) Silwet L-77 surfactant controlled hemp sesbania in soybeans an average of 95%. Aqueous fungal suspensions or adjuvants alone did not visually affect or control hemp sesbania. The soybean yields were significantly higher in the plots where weeds were effectively controlled. These results suggest that formulating C. truncatum in unrefined corn oil and surfactant greatly increases its infectivity and the biocontrol potential of this pathogen.     

The uptake of surfactants into wheat

The time course of uptake has been determined for seven poly(oxyethylene) surfactants, and one anionic surfactant (sodium dodecyl sulphate), into the leaves of wheat plants grown in a phytotron. Uptake was relatively rapid during an initial period of 24 h for six of the eight surfactants; after this period, the uptake rate was lower, and total uptake after 48 h was in the range 80-91% for those six surfactants. The other two compounds, sodium dodecyl sulphate and cetostearyl alcohol-22EO condensate (hexadecan-1-ol/octadecan-1-ol ethylene oxide condensate; average number of ethylene oxide units 22) were barely taken up at all. The observed time course for uptake was consistent with a complex process based on more than one rate-determining process. The physical properties of the surfactants are discussed in relation to their observed uptake behaviour. The surfactant deposit areas, measured by microscopy, were concluded to be not particularly relevant in interpreting the uptake results. Uptake was not related to surfactant chain length, but the physical form of the hydrated surfactant on a leaf surface appeared to influence uptake behaviour.