Assessment of pesticide use in the U.S. potato industry

Pesticide use in US fall crop potato production was surveyed for the years 1990 to 1994. The purpose of the study was to provide information about the relative importance of each pesticide and potential alternatives. The objectives were to: (1) inventory pesticides used on potatoes, (2) rank the target pests and (3) estimate the economic value of the major pesticides. Extension specialists working on potatoes in twelve states provided the main source of survey data. The most commonly used pesticides in four categories were: fungicide —chlorothalonil, insecticide —methamidophos, herbicide —metribuzin, and “other” -diquat. The most frequent target pests were: early blight (Alternaria solani), late blight (Phytophthora infestans), aphids (primarily Myzuspersicae), Colorado potato beetle (Leptinotarsa decemlineata), lambsquarter (Chenopodium album), and pigweed (Amaranthus spp.). The pesticides that provided the most annual value to potato growers were methamidophos ($281 million), diquat ($86 million), metribuzin ($81 million), CIPC ($56 million) and esfenvalerate ($52 million).     

Characterization and Distribution of Three New Clonal Lineages of Phytophthora infestans Causing Late Blight in Wisconsin from 2009 to 2012

Phytophthora infestans causes late blight of potato and tomato, a disease that has been estimated to cost U.S. potato growers $287.8 million annually. We collected isolates of P. infestans from Wisconsin from 2009 to 2012 and determined distribution of clonal lineages and mating types and sensitivity to the systemic fungicide mefenoxam. We also sought to evaluate the current utility of an analysis of the Glucose-6-phosphate isomerase (Gpi) allozyme locus for predicting mefenoxam sensitivity with the aim of delivering timely information to growers. Overall, 143 isolates were collected from 52 locations in 20 Wisconsin counties from 2009 to 2012. Three clonal lineages, US-22, US-23, and US-24, were identified and were novel to Wisconsin and the U.S. US-22 is of the A2 mating type and sensitive to mefenoxam, with Gpi 100/122. US-23 and US-24 are of the A1 mating type and primarily intermediately sensitive to mefenoxam, with Gpi 100/100 and 100/100/111, respectively. Because of this close correlation and the unique Gpi patterns for each lineage present, we were able to predict mefenoxam sensitivity directly from samples using the allozyme assay and quickly deliver management information to growers. Both mating types were present in Wisconsin in 2009 and 2010 but were spatially separated and no evidence of sexual recombination or soil persistence was detected. The presence of new clonal lineages of P. infestans in Wisconsin indicates a need for continued close monitoring of late blight to facilitate generation of timely information for enhanced short-term and long-term late blight management.     

几种杀菌剂防治马铃薯晚疫病试验

由于长期使用几种广谱性杀菌剂防治马铃薯晚疫病,导致该病病原菌抗药性增强,防效降低。为筛选高效、经济、安全的杀菌剂在生产上推广使用,试验选取了18.7%烯酰.吡唑酯WG、68.75%氟吡菌胺.霜霉威SC、72%甲霜灵锰锌WP、75%代森锰锌WG 4种药剂,设置高、中、低不同浓度,高浓度施药2次,中低浓度施药3次进行防治马铃薯晚疫病的田间药效试验。试验结果表明:18.7%烯酰.吡唑酯WG高、中、低浓底的防效分别为71.08%、73.03%、69.04%;其次为68.75%氟吡菌胺.霜霉威SC防效分别为62.09%、74.53%、64.65%,72%甲霜灵锰锌WP的防效分别为56.91%、71.71%、66.87%;75%代森锰锌WG的防效分别为46.52%、70.38%、68.85%。其中18.7%烯酰.吡唑酯WG和68.75%氟吡菌胺.霜霉威SC防效较好,其余2种药剂对马铃薯晚疫病均有一定的防效,建议生产上轮换使用。     

8种药剂对马铃薯晚疫病的防治效果试验

为减轻马铃薯晚疫病对马铃薯生产造成的损失,本研究选择了8种药剂,在马铃薯地上垄体栽培模式下进行晚疫病防治的药效比较试验。结果表明,不同处理均对地上垄体栽培模式下马铃薯晚疫病具有防治和保产的效果。其中,在马铃薯晚疫病发病前期喷施的保护性杀菌剂种中,60%百泰的防治和保产效果最好,防效达79%以上,增产43.54%;其次是银法利,防效达70%以上,增产42.55%。在发病中期喷施的治疗性杀菌剂中,防效和保产效果最好的药剂为50%安克,防效达73%以上,增产36.71%。     

不同杀菌剂对马铃薯晚疫病的防治效果

通过田间试验调查,研究了7种化学药剂对马铃薯植株和薯块晚疫病的防治效果。结果表明:7种药剂对马铃薯晚疫病均可达到显著防治效果。防治效果最好的4种药剂为25%瑞凡、50%福帅得、0.5%苦参碱和30%甲霜.嘧菌酯,防治效果均达到80%以上;其次为45%三苯乙酸锡和68.75%银法利,防治效果达到70%以上;较差为52.5%抑快净,防治效果达到65%。建议在生产上交替使用,避免产生抗药性。     

Challenges to Organic Potato Farming: Disease and Nutrient Management

For organic potato producers the two main challenges are disease and nutrient management. Both factors are limited by regulations that on the one hand prohibit the use of chemical fertilisers, especially nitrogen and, on the other hand, most synthetic pesticides. Late blight, caused by Phytophthora infestans is commonly thought to be the factor most limiting yield. However, because there is no really effective fungicide available to control late blight, there are virtually no yield loss data available for organic farming conditions. In this paper the state of the art of organic potato management with respect to disease and nutrient management is summarised. In a second part, the interactive effects of N-availability in the soil, climatic conditions and late blight were studied in the presence and absence of copper fungicides from 2002–2004 for the mid-early main-crop potato cv. Nicola. From the experimental work it became clear that copper fungicides in most cases do slow down epidemics adding an average of 3 days to the growth duration. However, only 30% of the variation in yield could be attributed to disease reduction. A model including disease reduction, growth duration and temperature sum from planting until 60% disease severity was reached, and soil mineral N contents at 10 days after emergence could explain 75% of the observed variation in yield. However, the model failed when N-supply was extremely high. The implications of the results on the management of organic potatoes with respect to cultivar choice, nutrient and disease management are discussed. In conclusion, several points emerge from the results: In organic farming, yields are foremost limited by nutrient availability in spring and early summer. The effects of late blight on yields may often be overestimated and cannot be deducted from results in conventional farming because of the strong interaction with nutrient status. Resistance clearly remains the most important strategy against late blight in organic potato production. However, as important or even more important than resistance is the early development and bulking behaviour and the ability of a cultivar to make use of organic nutrients efficiently. In the absence of efficient organic pesticides it is possible to reduce blight pressure to a certain extent by arranging the crop in small narrow fields perpendicular to the main wind direction neighboured either by non-hosts or completely resistant potatoes.     

Application of acibenzolar-S-methyl and standard fungicides for control of Phytophthora blight on squash

A plant systemic acquired resistance inducer, acibenzolar-S-methyl (ASM), was evaluated to determine the efficacy for suppression of Phytophthora blight of squash caused by Phytophthora capsici under field conditions. ASM was applied as foliar sprays before and after transplanting at rates of 17.5, 8.8, and 4.4 g a.i. ha⁻¹. Application of ASM did not significantly reduce final Phytophthora blight incidences in 2 out of 3 field experiments; however, area under the disease progress curve (AUDPC) values were reduced significantly by ASM in all experiments conducted. Disease suppression by the three application rates of ASM was not significantly different. To determine the effect of application of ASM in conjunction with standard chemical fungicides, ASM was applied with mefenoxam (Ridomil Gold), copper hydroxide, and mandipropamid (Revus). AUDPC values and final disease incidences were consistently lower in field plots treated by the combination of ASM and standard fungicides than applications of these chemicals alone. Application of ASM resulted in significantly higher squash yield than the non-treated control in 2 of 3 experiments and plots treated with the combined use of ASM and standard fungicides produced the highest yields. These results suggest that ASM may induce plant resistance under field conditions, providing suppression of Phytophthora blight of squash, and that there may be some benefit to the integration of ASM and standard chemical fungicides.     

Two decades of monitoring irish populations of<Emphasis Type="Italic">Phytophthora infestans</Emphasis> for phenylamide resistance

Summary Between 1981 and 1998,Phytophthora infestans populations in 878 potato crops in Ireland were monitored for phenylamide resistance. The incidence of resistance was very high in 1981 following intensive use of metalaxyl for blight control from 1977 onwards. It decreased rapidly in the absence of phenylamide use between 1981 and 1984. Following the reintroduction of phenylamide based fungicides in 1985, there was a rapid increase in phenylamide resistance following the widespread curative use of these fungicides. From 1990 onwards there was greater adherence among growers to the use of phenylamides in accordance with an antiresistance strategy and resistance distribution again decreased. During the 18-year period of the study, resistance was always lower at the beginning of the season and increased as the season progressed. Following the reintroduction of the phenylamide based fungicides in 1985 there was a steady increase in phenylamide use up to 1986 followed by a continuous decrease in use up to 1990. Since then there has been a steady increase in phenylamide use. They are currently used on some 60% of crops in Ireland and are still providing acceptable levels of disease control.     

Alternative treatments for late blight control in organic potato: Antagonistic micro-organisms and compost extracts for activity againstPhytophthora infestans

Summary The effects of various fungi, bacteria and different compost extracts on foliar infection of potato (Solatium tuberosum) withPhytophthora infestans were tested in detached leaf bioassays in 2001–2003. Application of microorganism inocula and compost extracts as well as copper oxychloride to excised leaves resulted in different degrees of blight control. In general, suppression of blight lesion growth was not improved by applying the antagonists before the leaves were inoculated withPhytophthora spores. There was some evidence that extracts made from different compost feed stocks of different ages suppressed leaflet infection with blight. However, results were very limited and inconsistent. Moreover, the effects were much smaller than where copper oxychloride was used. Improved efficacy of acceptable alternatives to copper fungicides especially in organic farming is required. No promising effective alternative to the use of copper fungicides to reduce late blight infection in organic potato production systems was identified in the experiments.     

不同杀菌剂对马铃薯晚疫病的田间防效试验

马铃薯晚疫病是马铃薯生产中一种普遍发生、危害严重的病害,杀菌剂防治该病仍是生产中采用的主要措施。本试验采用氟吡菌胺和霜霉威、噁霜·锰锌、烯酰吗啉和多菌灵4种农药,从发病初期开始连续进行2次施药防治晚疫病。结果表明,4种杀菌剂均有较好的防治效果,68.75%氟吡菌胺和霜霉威SC 1000倍、64%噁霜·锰锌WP 300倍、50%烯酰吗啉WP 1500倍和50%多菌灵WP 500倍施用2次后,平均防治效果分别为76.8%、70.0%、71.0%和62.0%,前3种杀菌剂的防效明显好于后者。     

河北省一季作区马铃薯病虫害发生及综合防控

河北省一季作区马铃薯主要病虫害有晚疫病、早疫病、黑痣病和二十八星瓢虫,此外,病毒引起的品种退化比较普遍,造成不同程度的损失。本文根据河北省一季作区马铃薯病虫害发生特点总结出一套综合防控技术体系,包括将马铃薯与玉米、大白菜等非茄科作物轮作3年减轻黑痣病危害;采用脱毒薯克服病毒引起的品种退化问题;种薯和(或)土壤消毒控制黑痣病和晚疫病;待马铃薯生长至封垄后,遇到适宜晚疫病发生的天气,喷施1～3次保护性杀菌剂预防晚疫病和早疫病;一旦监测到晚疫病中心病株后即拔除并装入塑料袋带出田外,并交替喷施有治疗效果、能兼治早疫病且作用机制不同的内吸性杀菌剂及混剂;田间出现马铃薯二十八星瓢虫成虫,在杀菌剂中混入高效氯氰菊酯或高效氯氟氰菊酯等高效杀虫剂防虫;马铃薯成熟前1～2周将地上部分割掉并运出田外后收获块茎。     

12个马铃薯品种对晚疫病抗性比较与药剂防治

通过田间试验,探讨常用马铃薯晚疫病防治药剂对不同马铃薯品种晚疫病防治效果,对产量影响及筛选出对马铃薯晚疫病有抗性的品种。结果表明,田间晚疫病发病初期,银法利单用或与其他药剂混用均可以有效控制马铃薯晚疫病,并且增加田间产量;‘荷兰7’,‘黄麻子’、‘荷兰15’和‘尤金’为马铃薯晚疫病易感品种,因此田间管理要提前预防马铃薯晚疫病的发生;‘克新18号’、‘麦肯’、‘延薯4号’和‘克新13号’对晚疫病有较高的抗性;‘中兴202’、‘Lt-5’、‘夏波蒂’和‘克新1号’对晚疫病表现中抗,病害发生初期施药可以有效的控制病害扩展。     

6种药剂防治马铃薯晚疫病药效试验

为减轻马铃薯晚疫病在生产过程中带来的减产、品质差等问题,特选择10%科佳悬浮剂等6种杀菌剂对马铃薯晚疫病进行药效比较试验。结果表明:不同药剂处理对马铃薯晚疫病都有防治效果和保产效果,其中10%科佳和72%克露对马铃薯晚疫病的防治和保产效果最显著,其次是抑快净和杀毒矾,再次是副帅得和可杀得。     

5种药剂对马铃薯晚疫病的防治效果分析

试脸在田间测定了克露、迭克宁、银法利、瑞凡和中药杀菌剂5种药剂对马铃薯晚疫病的防治效果。结果表明：5种药剂对马铃薯晚疫病均具有明显的防治效果和增产效果,防治效果最好的是银法利,其次为瑞凡、达克宁、克露和中药杀菌剂,增产62%-155％,晚疫病烂薯率为1．20％-8．09％。根据病害发展曲线,病害发展前期使用5种药剂。均可达到显著防治效果。病害发展后期,建议选择银法利和瑞凡药剂。注意每种药剂交替使用,避免产生抗药性。     

Changes in the distribution of phenylamide-resistant strains ofPhytophthora infestans (Mont.) de Bary in Ireland 1985–89

Summary Phenylamide-based fungicides were reintroduced to the Irish market in 1985. Mixtures of phenylamides and mancozeb were recommended for no more than 3 sprays in potato late blight control programmes with the last systemic spray to be applied not later than 31 July. Samples of potato foliage infected withP. infestans were collected from the main potato growing areas in Ireland over a five-year period starting in 1985. Using the floating disc method, 11% of the crops sampled in 1985 were found to have phenylamide-resistant strains ofP. infestans present. The number of crops with resistant strains increased rapidly up to 1988 when 83% of the crops sampled had resistance. Factors affecting the distribution of resistance and the efficacy of a phenylamide-based spray programme are discussed.     

Can Physiology Help Us to Combat Late Blight in Potato?

Late blight is a devastating disease in potato production world-wide. Breeding for resistance is complex because of the versatile and aggressive population of Phytophthora infestans, which overcomes any new genetic source of resistance very rapidly. There are reliable fungicides available to control the disease, but chemical control is costly and harmful to the environment. There are no cultural practices reducing the infestation, which are reliable enough to cope with the disease in a non-chemical way. Given the close link between the physiological condition of the crop and its resistance to late blight, this paper addresses the question whether crop physiology can help to combat the disease. Although there are possibilities to (partly) escape to the late blight by advancing the crop cycle or the tuber bulking, it is concluded that crop physiology can do little to reliably reduce the susceptibility to late blight. Breeding for resistance remains the best option.     

黑龙江省马铃薯晚疫病的发生与防治

马铃薯晚疫病是黑龙江省目前主要病害之一,每年发生和流行的程度均不同,但一般年份都会使得马铃薯产量减少20%左右,所以对于马铃薯晚疫病的防治工作越来越被重视。简单介绍马铃薯晚疫病的症状及发病规律,分析黑龙江省马铃薯晚疫病的发生情况,从品种选择、合理轮作、加强田间管理和化学防治等方面,提出综合防治策略和技术,以供种植者参考借鉴。     

6种杀菌剂对马铃薯晚疫病菌的室内毒力测定

采用菌落直径法测定了金雷多米尔、杀毒矾、克露、克霜氰、大生M-45和进富6种杀菌剂对马铃薯晚疫病菌的毒力。结果表明供试的6种杀菌剂对马铃薯晚疫病菌丝生长都有较好的抑制作用,克露对晚疫病菌毒力最强,其EC50值为0.16μg·mL-1,毒力最差的是大生,其EC50值为2.89μg·mL-1,其余4种药剂按毒力大小依次为克霜氰、金雷多米尔、进富和杀毒矾,其EC50值分别为0.24μg.mL-1、0.28μg·mL-1、0.43μg·mL-1和1.17μg·mL-1。根据室内毒力测定结果及药剂特性,供试的6种杀菌剂在生产上可视病害的发生情况交替使用,以避免或延缓抗药性的产生。     

不同药剂对马铃薯晚疫病的防治效果试验

为比较多种马铃薯晚疫病常用防治药剂在不同浓度下对晚疫病的防治效果,选择了4种常用药剂采用随机区组设计,进行不同浓度下的防治对比试验。结果表明:687.5 g/L银法利悬浮剂和75%代森锰锌水分散粒剂效果较好,综合农药用量和防治用工等防治成本考虑,在生产中,采用687.5银法利悬浮剂开展防治,以125 mL/667 m2施2次和75 mL/667 m2施3次最为适宜,采用75%代森锰锌水分散粒剂开展防治,以100 g/667 m2施3次和200 g/667 m2施2次最为适宜。     

Potassium phosphite combined with reduced doses of fungicides provides efficient protection against potato late blight in large-scale field trials

Potato late blight caused by the oomycete Phytophthora infestans is a devastating disease of potato worldwide. Most of the potato cultivars grown in conventional agriculture are susceptible, or at best moderately resistant, and require frequent applications of fungicides to avoid heavy yield losses.In field trials spanning four years, we have investigated the effect of potassium phosphite, an inorganic salt on potato late blight. Potassium phosphite is known to induce defence responses in potato and to also have direct toxic effects on oomycetes, which in turn counteract late blight and tuber blight development. However, the use of this salt is not yet implemented and approved in European potato cultivation. We compared the effect of phosphite alone with fungicides currently used in Swedish potato cultivation. We also investigated the combined use of potassium phosphite and reduced doses of fungicides. Table potato cultivars and starch potato cultivars with different levels of resistance were used.We found that potassium phosphite in combination with reduced doses of fungicides results in the same level of protection as treatments with the recommended full dose of fungicides. These combined treatments reduce the need of traditional fungicides and may also decrease the selection pressure for fungicide resistance development in the pathogen. In relatively resistant starch potato cultivars using phosphite alone gave sufficient protection against late blight. Furthermore, in starch potato a combination of phosphite and fungicides at two-week intervals provided similar protection to weekly applications of fungicide at the recommended dose. Foliar treatment with phosphite also gave protection against tuber blight at similar levels to that of the best-performing fungicide. Our data suggests that potassium phosphite could be used in potato cultivation in temperate regions such as in Sweden, at least in combinations with reduced rates of fungicides. The implementation of the use of phosphite in practical potato crop protection as part of an IPM strategy is discussed. Doses, intervals and combinations could be adjusted to the level of cultivar resistance.