Calendar Spray Research Articles

Comparisons of economic thresholds for Asian citrus psyllid management suggest a revised approach to reduce management costs and improve yield

Huanglongbing (HLB) or citrus greening disease is transmitted by the Asian citrus psyllid, Diaphorina citri Kuwayama. Vector control is considered a basic component of HLB management even under high disease incidence scenarios. While vector management heavily relies on the application of synthetic chemical sprays, overuse of insecticides raises several concerns including insecticide resistance, environmental impacts, and secondary pest outbreaks. The present study aims to compare the effects of three different economic thresholds (ET-0.2, 0.5, 1.0) and one calendar-based application schedule on the incidence of D. citri and beneficial species in plots of commercially grown citrus, as well as end-of-season yield and overall management costs. The results suggest that reducing spray frequency from eight to as few as three sprays per year had little effect on counts of pest and beneficial insects in the field. The numbers of D. citri and that of a secondary weevil pest were similar between plots treated with the calendar-based spray plots and plots managed with the ET-1.0. Furthermore, spider numbers were higher in the ET-1.0 plots, while ant numbers were lower compared with calendar sprayed plots. Management input costs were lower under economic thresholds (ET-0.5–ET-1.0) than with monthly calendar-based sprays, while yield losses were only slightly greater in the lower threshold of 0.2 mean psyllids per tap than with calendar sprays. Overall, management savings of more than 100% made up for this difference. Together, these results suggest that implementing a spray program of rotated chemistries based on an economic threshold of 0.5–1.0 adult psyllids per stem tap could provide both economic and ecological benefits. We discuss the implications of such an approach in the context of a young citrus tree protection program and the greater goals of sustainable citrus production under HLB.

First record of blueberry maggot in Lac Saint-Jean, Quebec

Up to 2017, the Lac Saint-Jean region (Quebec, Canada) produced lowbush blueberries ( Vaccinium angustifolium Aiton) without insecticide treatments. In 2018, the Canadian Food Inspection Agency detected adults of the blueberry maggot ( Rhagoletis mendax Tephritidae) in the Regional County Municipality (RCM) of Maria-Chapdelaine. Monitoring programs of adults and larvae conducted in 2019, 2020, and 2021 confirmed the establishment of R. mendax in the RCM of Maria-Chapdelaine, as well as in the RCM Domaine-du-Roy. In compliance with Directive D-02-04 of the Canadian Food Inspection Agency, blueberry growers of infested areas of Lac Saint-Jean that ship blueberries to noninfested areas must implement an integrated pest management program or a calendar spray program.

A simple, hand-held decision support designed tool to help resource-poor farmers improve potato late blight management

Many decision support systems (DSS) have been developed to manage potato late blight caused by Phytophthora infestans, but most of these require sophisticated equipment and are not realistic alternatives for small-scale farmers in low-income countries. This research evaluates a simple, hand-held decision support tool (HH-DST) consisting of a disk with three concentric circles, two of which represent factors that drive late blight epidemics and the third providing a spray recommendation. Three disks of different colors have been designed for potato varieties of varying levels of host resistance. The HH-DST was compared with locally used fungicide spray regimes in three trials in Peru, and in six trials in Ecuador, where the tool had been slightly modified. In two additional trials in Peru, the HH-DST was compared with local practices, calendar spraying and two other DSS. The HH-DST and local spray regimes both gave relatively good disease control in all cases, however, the HH-DST was more effective with highly susceptible cultivars both in Ecuador and Peru. The HH-DST also had equal or lower number of sprays per season and had a lower environmental impact, based on the environmental impact quotient (EIQ), than did the local practices. Results were similar in trials comparing different DSS, where all approaches, including the HH-DST, adequately controlled disease, and the HH-DST was among the lowest for both number of sprays per season and environmental impact. The HH-DST is a simple tool that can help resource-poor farmers improve management of potato late blight.

Density threshold-based acaricide application for the two-spotted spider mite Tetranychus urticae on cassava: from laboratory to the field.

The red spider mite Tetranychus urticae is known as a worldwide pest in cassava production which can caused serious economic losses. Because no threshold levels are established for T. urticae in cassava cropping, many growers in China are applying excessive chemical applications per cassava cropping period. This is not only expensive, but also results in lower yields because of severe leaf damage and development of resistance. This study aims to develop an immediate threshold level for T. urticae control which could be determined in the laboratory and fit the field application requirements. The mite density of 25 mites/leaf was the threshold which caused significant decrease of photosynthetic pigment contents and protective enzyme activities in cassava leaves in the laboratory. Moreover, 25 mites/leaf was also the threshold density which resulted in significantly lower leaf damage and higher yield levels compared with a higher level of mites/leaf where calendar sprays were used. The mite density threshold that brought about significant physiological and biochemical changes in the laboratory basically coincided with the threshold that resulted in significant yield loss in the field. It is therefore concluded that the optimum threshold acaricide spray for T. urticae on cassava is 25 mites/leaf. © 2019 Society of Chemical Industry.

Monitoring and Controlling the Beet Leafhopper Circulifer tenellus in the Columbia Basin

The beet leafhopper (BLH, Circulifer tenellus Baker) is a frequent pest of potatoes in the Columbia Basin of Oregon and Washington. Beet leafhoppers vector the causal agent of potato Purple top disease, known as Beet Leafhopper Transmitted Virescence Agent (BLTVA). Over 70 % of BLH in the region can be infected with BLVTA. Current control methods include making regular insecticide applications beginning in May; however it is unclear if those applications are needed. Thus, are insecticide applications necessary to control BLH and reduce BLTVA through the entire season? To answer that question, a field study was conducted in 2008 and 2009 to assess season-long control of BLH. There were 14 treatments, including the control, that were based on gradually eliminating insecticide applications weekly. Plots were sampled weekly for BLH and surveyed for Purple Top disease. Beet leafhoppers were sampled using sweep nets and an inverted leaf blower. Natural BLH populations were low in 2008 and 2009, but differed significantly among treatments in 2009 for inverted leaf blower and sweep net samples. Yields were assessed at the end of each season and no significant differences were found. Trends in the yield, BLH populations and BLTVA incidence support early-season insecticide application when BLH populations are low. The practice of using a calendar spray regime was not supported as yields were similar regardless of insecticide applications. As BLH populations were low, the results emphasized the importance of monitoring before making insecticide applications.

감귤원에서 썩덩나무노린재 감귤과실 흡즙이 낙과 및 부패에 미치는 영향

This study was conducted to examine the feeding effect of Halyomorpha halys (Stal) (Hemiptera: Pentatomidae) on the fruit drop and decay rate of Mandarin citrus fruits (Citrus unshiu). The feeding of H. halys before fruit coloring caused a severe fruit drop, while the feeding after fruit coloring induced a low level of fruit drop. However, the feeding of H. halys before or after fruit coloring did not induce significant fruit decay during cold storage. The results are expected to be useful in managing H. hlays of late season mandarine, because citrus farmers follow calendar spray to prevent fruit drop and fruit decay.

Toward an Integrated Use of Biological Control by Cladosporium cladosporioides H39 in Apple Scab (Venturia inaequalis) Management.

Apple scab, caused by Venturia inaequalis, is the most important disease in apple production, reducing yield and quality of fruit. Control of apple scab in commercial orchards currently depends on multiple applications of fungicides. The potential of the antagonistic isolate Cladosporium cladosporioides H39, originating from a sporulating colony of V. inaequalis, to control apple scab development was tested in eight trials during 2 years in orchards in Eperjeske (Hungary), Dabrowice (Poland), and Bavendorf (Germany) planted with different cultivars. Treatments were conducted as calendar sprays or after infection periods. Additional trials in an orchard in Randwijk (The Netherlands) focused on the effect of timing of antagonist application before or after infection periods. The overall results of the field trials consistently showed-for the first time-that stand-alone applications of the antagonist C. cladosporioides H39 can reduce apple scab in leaves and fruit. This was demonstrated in an organic growing system as well as in conventional orchards by spray schedules applied during the primary or the summer season. In both systems, the same control levels could be reached as with common fungicide schedules. Efficacies reached 42 to 98% on leaf scab incidence and 41 to 94% on fruit scab. The antagonist was also effective if applied one or even several days (equivalent to approximately 300 to 2,000 degree h) after infection events in several field trials and a trial conducted in Randwijk with single-spray applications at different intervals before or after infection events. Better understanding of the biology of the antagonist will help to further exploit its use in apple scab control.

THRESHOLDS FOR VECTOR CONTROL AND COMPATIBILITY WITH BENEFICIAL FAUNA IN CITRUS WITH HIGH INCIDENCE OF HUANGLONGBING

Huanglongbing (HLB) or citrus greening disease is vectored by the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. Vector control is considered a basic component of HLB management even in a high disease incidence scenario. Such control is mostly chemically oriented. However, overuse of insecticides would increase costs and be incompatible with biological control. Establishment of economic thresholds for psyllid control under different price scenarios would optimize returns on investment. A 3-year experiment is being conducted in a commercial orange block with high HLB incidence. Experimental design is RCB with 4 treatments and 4 replicates: (1) calendar applications, (2) insecticide applications according to a threshold of 0.2 psyllids/stem tap sample, (3) applications according to a 0.7 threshold and (4) no insecticide. Vector populations are monitored biweekly by tap sampling. Differences in vector abundance among treatments are being correlated to fruit yields. Consequences of each vector control strategy on beneficial arthropod fauna are also being evaluated, as well as potential negative impacts on biological control. After two years, a significant yield increase was observed with the calendar treatment, but so far, justification for the additional costs would require higher than actual juice prices scenarios. ACP management strategies based on nominal thresholds are so far more profitable. Negative impacts of calendar sprays on biological control of mites and leafminers have been observed.

Insecticide sprays, natural enemy assemblages and predation on Asian citrus psyllid, Diaphorina citri (Hemiptera: Psyllidae).

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama is considered a key citrus pest due to its role as vector of 'huanglongbing' (HLB) or citrus greening, probably the most economically damaging disease of citrus. Insecticidal control of the vector is still considered a cornerstone of HLB management to prevent infection and to reduce reinoculation of infected trees. The severity of HLB has driven implementation of intensive insecticide programs against ACP with unknown side effects on beneficial arthropod fauna in citrus agroecosystems. We evaluated effects of calendar sprays directed against this pest on natural enemy assemblages and used exclusion to estimate mortality they imposed on ACP populations in citrus groves. Predator exclusion techniques were used on nascent colonies of D. citri in replicated large untreated and sprayed plots of citrus during the four major flushing periods over 2 years. Population of spiders, arboreal ants and ladybeetles were independently assessed. Monthly sprays of recommended insecticides for control of ACP, adversely affected natural enemy populations resulting in reduced predation on ACP immature stages, especially during the critical late winter/early spring flush. Consequently, projected growth rates of the ACP population were greatest where natural enemies had been adversely affected by insecticides. Whereas, this result does not obviate the need for insecticidal control of ACP, it does indicate that even a selective regimen of sprays can impose as yet undetermined costs in terms of reduced biological control of this and probably other citrus pests.

Evaluation of epidemics and weather-based fungicide application programmes in controlling anthracnose fruit rot of day-neutral strawberry in outdoor field and protected cultivation systems

Anthracnose fruit rot caused by Colletotrichum acutatum is an economically important disease of strawberry in Ontario. Three years of experiments (2009–2011) were conducted at the University of Guelph’s Cedar Springs Research Station in Blenheim, ON to understand anthracnose fruit rot epidemics in outdoor field and protected production systems and to evaluate different fungicide spray programmes for disease control in day-neutral strawberry. Weather-based fungicide timing programmes were compared with calendar spray programmes in two day-neutral cultivars, ‘Seascape’ and ‘Albion’. Incidence of disease in high-tunnels was very low in all 3 years, even in fungicide non-sprayed plots, indicating that cultivation of day-neutral strawberry in high-tunnels could be an alternative strategy for controlling anthracnose fruit rot with minimal use of fungicides. In outdoor fields, disease incidence was greatly influenced by leaf wetness duration, rainfall and temperature. The use of a weather-based model to determine the timing of fungicide treatments reduced the number of sprays and was as effective as a calendar-based spray at 7-day intervals to reduce the disease and increase marketable fruit yield. Rotating fungicides with different modes of actions (pyraclostrobin, myclobutanil and boscalid + pyraclostrobin) was more effective in reducing disease than regular sprays of captan. The outcomes of this research will be useful to develop decision support tools and select proper fungicides and cultivation systems to manage anthracnose.

Evaluation of Management Programs for Protecting Young Citrus Plantings from Huanglongbing

Asiatic huanglongbing (HLB) is a devastating disease of citrus associated in North America with the bacterium ‘Candidatus Liberibacter asiaticus’ (LAS) vectored by the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. ACP management is considered a vital component of a program aimed at reducing the incidence and spread of HLB. Considerable research has been published comparing the efficacy of different insecticides for ACP control as well as on seasonal strategies for applying ACP insecticides. However, published information was largely lacking for even the most intense insecticide programs on their effectiveness for keeping HLB out of a new citrus planting in Florida citrus. We therefore conducted two replicated (individual plots 0.2 to 0.4 ha in size) experiments on protecting young citrus from HLB using different ACP management programs. An intensive insecticide program was evaluated in each experiment: eight annual calendar applications of traditional insecticides (hereafter referred to as the “complete” program). In one experiment, citrus was either planted alone and subjected to the complete program or citrus was interplanted with orange jasmine, Murraya exotica L. (a favored ACP host plant) and subjected to a reduced insecticide program (four calendar sprays of traditional insecticides). There was one set of plots in which both jasmine and citrus were treated with insecticides and one set in which jasmine was not treated at all. In the second experiment, citrus was either subjected to the complete program or to one of two other programs: a reduced insecticide program consisting of five calendar applications of traditional insecticides or a mineral oil program (oil applications every 3 weeks plus one dormant insecticide spray). The results of the two experiments were similar. Relatively good ACP control was achieved under each ACP management program during the first year but, as the experiments progressed and trees increased in size, ACP outbreaks occurred regardless of the psyllid management program. Little HLB developed under any ACP management program during the first year, but thereafter HLB increased and large percentages of the trees in each experiment became LAS-infected in less than two to three years. The combined results of the experiments indicated that up to eight monthly pesticide treatments per year applied on a calendar schedule were ineffective for preventing young citrus from becoming diseased. Of important significance is that the orchard within which the two experiments were conducted was subjected to a minimal psyllid management program and contained many older trees known to be infected by the HLB pathogen, a challenging situation for getting young trees into production without contracting the disease. Thus, the ACP management programs we evaluated might have been more effective if ACP in the surrounding areas had been more aggressively controlled and diseased trees in the surrounding areas removed to reduce inoculum loads. Also, the programs might have been more effective for slowing the spread of HLB if our research plots had been larger.

Tomato potato psyllid (<i>Bactericera cockerelli</i> Sulc) impacts on taewa seed quality and performance preliminary results

Taewa (Solanum tuberosum L Maori potatoes) are susceptible to tomato potato psyllid (Bactericera cockerelli Sulc TPP) infestation and to infection with the bacterium Candidatus Liberibacter solanacearum (Lso) vectored by the psyllid Current growing systems used by taewa growers leave the crop highly vulnerable to TPP and Lso infection leading to potential reductions in seed tuber quality and harvestable yield Seed tubers for two virusfree taewa lines (Moemoe and Tutaekuri) grown under high (calendar spraying of insecticides) and low (reduced insecticide spray regime) levels of TPP protection in a zebra chip small plot trial during 2011/12 in Pukekohe were stored after harvest Tubers were later sorted into two seed size categories small (

Seeds of Neem Tree (Azadirachta indica A. Juss). Promising Biopesticide in the Management of Cowpea Insect Pests and Grain Yield in the Early Cropping Season at Asaba and Abraka, Delta State, Nigeria

Literature on the use of neem extract as biopesticide in the management of field insect pests on cowpea in Nigeria is scanty. The present study evaluated the efficacy of extract of neem seeds at 5 percent concentration for the control of the cowpea aphid, Aphis craccivora Koch, flower bud thrips, Megalurothrips sjostedti Tryb, legume pod borer, Maruca vitrata Fab, and a spectrum of pod sucking bugs (Coreidae bugs) all key field insect pests of cowpea. The experiments were conducted in the early cropping season in two locations – Asaba and Abraka, Delta State, Nigeria. At Asaba, the study took place in the Teaching and Research Farm of the Agronomy Department, Asaba Campus and at Abraka on a plot of land situated close to the Agricultural Sciences Department, Delta State University, Abraka. The experiments consisted of two calendar sprays – 7 days’ spray intervals at 5 times and 10 days’ spray intervals at 4 times and monitored spray and a control. There were 4 treatments and 3 replicates, organised into a randomised complete block design (RCBD). The results indicated that more insect pests occurred at Asaba than Abraka plot. The calendared spray treatments significantly (P<0.05) reduced M. sjostedti at Asaba and A. craccivora colonies at Abraka plot compared to control. Grain yield was significantly higher at Abraka (1630.70kg ha -1 ) compared to Asaba (404.90 kg ha -1 ). The neem seed extract at 5 percent concentration in the management of the cowpea insect pest is quite attractive. However, the botanical causes delay in cowpea flowering.

Management of major field insect pests and yield of cowpea (Vigna unguiculata (L) walp) under calendar and monitored application of synthetic chemicals in Asaba, southern Nigeria

The management of major field insect pests of cowpea under calendar and monitored sprays of cypermethrin was studied. The major insect pests studied were the co wpea aphid, Aphis craccivora Koch, legume bud thrips Megalurothrips sjostedti Tryb, legume pod borer, Maruca vitrata Fab. and pod sucking bugs. Influence of insect pe st management on yield was also determined. The calendar sprays consisted of 7 days' spray intervals carried out 5 times and 10 d ays' spray intervals, carried out 4 times. Monitored spray was carried out only when insect pest infestation/damage reached or exce eded the action threshold. The experiments were conducted in the Teaching and Research Farms of the Agronomy department, Asaba Campus, Delta State University, Nigeria. Comparison of insect pests and grain yield from the calendar and monitored spray treatments was made if differences existed among them. Results indicated that all the cypermethrin treatments effectively c ontrolled M. sjostedti , M. vitrata , flower bud thrip population and pod sucking bugs when compared to control in the early season. Ther e was however, no significant difference (P>0.05) in calendar and mon itored sprays. Similar observation was made for gr ain yield. In the late season, all treatments significantly (P<0.05) contr olled pest population/damage on cowpea. Grain yiel d increase was similarly recorded but no differences among the treatments. Cowpea growers sometimes apply insecticides as many as 8 to 10 times to control insect pests during the growing season; the study here provides evidence (1) that 10 days' int erval spray and monitored spray can be as profitable as 7 days' interval spra y in cowpea production and (2) this could reduce th e number of chemical application, save cost as well as environmental pol lution and hazards to consumers.

Evaluation of neem seed extract for the control of major field pests of cowpea (&lt;i&gt;Vigna unguiculata&lt;/i&gt; L. Walp) under calendar and monitored sprays

Cowpea growers sometimes apply chemicals as many as 8-10 times to control insect pests during the growing season. Calendar sprays at 7 days' intervals (CA.S7) carried out 5 times and 10 days' intervals (CA.S10) carried out 4 times and monitored spray (MOS) carried out only when insect infestation/damage reached or exceeded the action threshold were studied to find out their effect on major insect pests and yield of cowpea - whether there were differences in the number of insect pests and grain yield. The insect pests studied were the cowpea aphid, Aphis craccivora Koch, legume bud thrips Megalurothrips sjostedti Tryb, legume pod borer, Maruca vitrata Fab. and pod sucking bugs under the application of 5% aqueous extract of neem seed kernel extract (NSKE). The trials were conducted during the early and late planting seasons in Abraka, on a piece of land half a kilometre to Campus 2, Delta State University, Nigeria. The results indicated that calendar sprays significantly controlled A. craccivora colonies compared to control in the early season. Population of other major insect pests was generally low. During the late season, the various NSKE treatments effectively controlled A. craccivora. No significant difference among the treatments in their effect on the other major insect pests. Grain yields were high in both seasons and a significant difference did not exist among the calendar and monitored spray treatments. Three main things are obvious from this study: (1) neem seed kernel extract is effective in the control of cowpea insect pests, especially A. craccivora, (2) Grain yields were similar in calendar and monitor sprays. (3) spraying every 10 days for 4 times and monitoring insect pest damage/infestation before spraying reduced the number of chemical application.Keywords: Cowpea, insect pests, neem extract, calendar and monitored sprays.

Rainfall Thresholds as Support for Timing Fungicide Applications in the Control of Potato Late Blight in Ecuador and Peru.

Accumulated rainfall thresholds were studied in seven field experiments conducted in Ecuador and Peru for their value in timing applications of fungicide to control potato late blight, caused by Phytophthora infestans. Fungicide regimes based on accumulated rainfall thresholds ranging from 10 to 70 mm were compared with calendar spray schemes of every 5 or 7 days. Very low thresholds of 10 to 20 mm gave similar levels of control and resulted in similar number of sprays as did calendar spraying. However, neither low thresholds nor calendar sprays were effective in protecting susceptible potato genotypes in over half of the experiments. Thresholds of 25 to 50 mm of rainfall led to reduction in the number of sprays needed to protect resistant cultivars but also resulted in high levels of disease on susceptible cultivars. We conclude that timing fungicide sprays based on accumulated rainfall thresholds could be a successful component of integrated management strategies that include cultivars with moderate or high levels of resistance. The simplicity of measuring accumulated rainfall means that the technology can potentially be used by resource-poor farmers in developing countries.

미국 북서부지역에 발생하는 서부양벚과실파리의 발생 월동 후 발생 동태에 관한 연구

서부양벚과실파리(Rhagolettis indifferens Curran)은 미국 북서부지역 및 California 북부에서 재배되는 단체리(Prunus avium)에 가장 큰 피해를 주는 해충이다. 체리의 수출을 위한 식물검역에서 Zero Tolerance의 규제를 받고 있는 이 해충의 방제를 위해 농가에서는 월동 후 우화 시점부터 지속적으로 약제를 살포하고 있으며, 살충제 처리의 적기를 예측할 수 있는 모형이 절실히 필요한 실정이다. 본 연구는 서부양벚과실파리를 대상으로 월동 후 성충의 우화 및 발생시기, 유충의 밀도변화, 번데기의 용화시기 및 밀도변화 등을 정량적으로 추적하여 개체군 밀도의 경시적 변동과 월동 후 우화시기를 예측하는 모형 검정의 기초자료로 사용코자 수행하였다. 이를 위하여 황색끈끈이트랩, 우화케이지, 용화트랩 등을 이용하여 실제 과원에서 각 태별 발생경과를 경시적으로 조사하였으며, 체리 과실이 달리는 시기부터 일정 간격으로 과실을 수거하여 시기별 과실 내부의 유충 수를 조사하였고, 실내에서 용화케이지를 이용하여 용화시기를 조사하였다. 그 결과 월동 성충의 우화는 5월 중순에 시작하여 6월 초순에 정점에 도달하였고, 6월 중순부터 7월 상순까지 과실 당 1마리 이상의 유충이 존재하였다. 7월 중순에 번데기의 수가 정점에 도달하였으며, 월동 중에 토양습도 등의 조건에 따른 번데기의 발육속도 및 생존율을 측정하기 위해 대량의 번데기를 확보하였다. 이 연구에서 얻어진 자료에서 나타난 과실파리의 월동 후 개체군 밀도변동과 용화시기를 Song et al.(2003)의 모형에서 예측한 결과와 비교한 결과 모형에 의해 예측된 발생일과 실측 발생일과는 1<TEX>$\sim$</TEX>2일 차이로 매우 정확하게 예측이 되었다. 이로 미루어 볼 때 본 연구에서 획득한 포장 실측자료는 누적 우화일, 유충의 발육단계, 산란일 등 다른 중요한 생물학적 사건을 예측하는 모형의 정확도 검정에도 잘 활용될 수 있을 것으로 생각된다. The western cherry fruit fly, Rhagoletis indifferens Curran (Diptera:Tephritidae), is the most important pest of cultivated cherries in the Pacific Northwest area of the United States, being widely distributed throughout Oregon, Washington, Montana, Utah, Idaho, Colorado and parts of Nevada. The control of R. indifferens has been based on calendar sprays after its first emergence because of their zero tolerance for quarantine. Therefore, a good prediction model is needed for the spray timing. This study was conducted to obtain the empirical population dynamic information of R. indifferens after overwintering in the major cherry growing area of the Pacific Northwest of the United States, where the information is critically needed to develop and validate the prediction model of the fruit fly. Adult fly populations were monitored by using yellow sticky and emergence traps. Larvae growth and density in fruits were observed by fruit sampling and the pupal growth and density were monitored by pupal collection traps. The first adult was emerged around mid May and a large number of adults were caught in early June. A fruit had more than one larva from mid June to early July. A large number of pupae were caught in early July. The pupae were collected in various period of time to determine the effect of pupation timing and the soil moisture content during the winter. A series of population density data collected in each of the developmental stage were analyzed and organized to provide more reliable validation information for the population dynamic models.

Evaluation of disease forecasting programs for management of septoria late blight (Septoria apiicola) on celery

Septoria late blight caused by Septoria apiicola damages celery leaves (Apium graveolens), but its main impact is on the marketability of petioles. Three field trials (two in 2005 and one in 2006) were conducted at the Holland-Bradford Marsh, Ontario, to determine whether the number of fungicide applications required to manage septoria late blight could be reduced compared with the standard calendar spray program and whether disease management could be improved. Two disease forecasting programs (Tomcast at three disease severity value (DSV) thresholds and the Septoria Predictor) were assessed relative to a 7-day calendar spray program and a nonsprayed control. Each fungicide timing treatment, which entailed application of the fungicide Bravo 500 (chlorothalonil 50% a.i.) alternating with Champ 2FL (copper hydroxide 37.5% a.i.), was compared with Pristine WG (pyraclostrobin 12.8%, boscalid 25.2% a.i.) alternating with Champ 2FL on each of two celery cultivars. Pristine consistently provided superior control of septoria late blight compared with Bravo. Treatments were applied to two susceptible celery cultivars ‘Florida 683’ and ‘Sabroso’. Both cultivars responded in a similar manner to the treatments. Fungicide applications timed according to Tomcast at a DSV threshold of 10 or the Septoria Predictor resulted in septoria late blight severity levels on leaves and petioles comparable to the calendar spray program. Fungicide applications were reduced by 1 for the Septoria Predictor, by 1 to 3 for Tomcast at DSV threshold 10, and by 2 to 4 for Tomcast at DSV threshold 15. However, a yield reduction of 15% occurred in one trial when application of Bravo/Champ were timed according to Tomcast at DSV 15, indicating that the DSV 15 threshold was not always adequate for septoria late blight management using Bravo. Key words: disease management, Tomcast, Septoria Predictor, integrated pest management, fungicide, Apium graveolens var. dulce. La septoriose (brûlure tardive) (Septoria apiicola) endommage les feuilles de céleri (Apium graveolens), mais c'est sur la qualité marchande des pétioles que son impact principal se fait sentir. Trois essais au champ (deux en 2005 et un en 2006) furent effectués dans le marais Holland-Bradford, Ontario, afin de déterminer si le nombre d'applications de fongicides nécessaires pour lutter contre la septoriose pouvait être réduit comparativement au calendrier courant de pulvérisations et si la lutte contre la maladie pouvait être améliorée. Deux programmes de prévision des maladies (le Tomcast à trois seuils de valeur d'intensité de maladie (DSV) et le Septoria Predictor) furent évalués en ce qui a trait à un calendrier d'applications de 7 jours et un témoin non traité. Pour chaque traitement fongicide prévu, l'application du fongicide Bravo 500 (chlorothalonile à 50 % de matière active) en alternance avec le Champ 2FL (hydroxyde de cuivre à 37,5 % de matière active), fut comparée au Pristine WG (pyraclostrobine à 12,8 %, boscalide à 25,2 % de matière active) en alternance avec le Champ 2FL sur chacun des deux cultivars de céleri. Le Pristine a invariablement procuré une meilleure lutte contre la septoriose comparativement au Bravo. Les traitements furent appliqués à deux cultivars de céleri sensibles, ‘Florida 683’ et ‘Sabroso’. Les deux cultivars ont eu une réponse similaire aux traitements. Les applications de fongicides prévues par le Tomcast à un seuil de DSV de 10 ou par le Septoria Predictor ont donné des degrés de septoriose sur les feuilles et les pétioles comparables à ceux obtenus avec le calendrier courant de pulvérisations. Le nombre d'applications de fongicides fut réduit de 1 dans le cas du Septoria Predictor, de 1 à 3 dans le cas du Tomcast à un seuil de DSV de 10, et de 2 à 4 dans le cas du Tomcast à un seuil de DSV de 15. Cependant, dans un essai, une réduction du rendement de 15 % s'est produite lorsque l'application de Bravo/Champ fut prévue en fonction du Tomcast au seuil DSV de 15, ce qui indique que le seuil de DSV de 15 n'était pas toujours adéquat pour lutter contre la septoriose en utilisant le Bravo. Mots-clés : lutte contre les maladies, Tomcast, Septoria Predictor, lutte intégrée contre les parasites, fongicide, Apium graveolens var. dulce.

PEST MANAGEMENT IN QUEENSLAND STRAWBERRIES: REALITY BITES, AND GROWERS´ PERSPECTIVES CHANGE!

Prior to the 1980s, arthropod pest control in Queensland strawberries was based entirely on calendar sprays of insecticides (mainly endosulfan, triclorfon, dimethoate and carbaryl) and a miticide (dicofol). These chemicals were applied frequently and spider mite outbreaks occurred every season. The concept of integrated pest management (IPM) had not been introduced to growers, and the suggestion that an alternative to the standard chemical pest control recipe might be available, was ignored. Circumstances changed when the predatory mite, Phytoseiulus persimilis Athios-Henriot, became available commercially in Australia, providing the opportunity to manage spider mites, the major pests of strawberries, with an effective biological agent. Trials conducted on commercial farms in the early 1980s indicated that a revolution in strawberry pest management was at hand, but the industry generally remained sceptical and afraid to adopt the new strategy. Lessons are learnt from disasters and the consequent monetary loss that ensues, and in 1993, such an event relating to ineffective spider mite control, spawned the revolution we had to have. Farm-oriented research and evolving grower perspectives have resulted in the acceptance of biological control of spider mites using Phytoseiulus persimilis and the 'pest in first' technique, and it now forms the basis of an IPM system that is used on more than 80% of the Queensland strawberry crop.

Advances in conventional methods of disease management

Conventional agriculture, including disease management, is in a constant state of change as a result of scientific developments, societal pressures, and financial constraints. Progress in managing disease while protecting the environment has occurred in two main areas, the development and registration of reduced risk fungicides and improvements in integrated pest management and integrated crop management programs. There has been expedited registration of several effective reduced-risk fungicides in both Canada and the United States, and growers have rapidly adopted their use. The integrated crop management approach expands on integrated pest management for crop production with the goal of optimizing plant health and economic returns, with a minimum negative effect on the environment. Disease management can be improved through understanding the effects of nutrients such as nitrogen and calcium on disease development and by using fertilizers and other materials that stimulate host-plant resistance. Surveys indicate that the majority of farmers in both Ontario and California use fewer pesticides than are recommended by calendar spraying. In California, there was no reduction in pesticides used for disease management from 1993 to 2000, but growers did switch to newer pesticides. Pesticide use in Ontario declined by 2000 t of active ingredient from 1993 to 2003, a change that is partially attributed to integrated pest management programs.