Pathogenic variability of Ascochyta rabiei in Saskatchewan

Non-Peer ReviewedForty isolates of Ascochyta rabiei collected in Saskatchewan Canada and 18 obtained from other countries were assessed for pathogenicity on eight chickpea differential lines/cultivars under controlled conditions. Each assessment was repeated once. Based on the differential by isolate interactions, 15 distinct pathotypes were identified among the isolates from Saskatchewan. This demonstrates that many races of A. rabiei are present in Saskatchewan. Formation of new virulent races through gene recombination is possible. This will have large impact on Ascochyta blight development and its control. Plant breeders should anticipate a highly diverse A. rabiei population with a high potential for change

Fungicides application timing, sequencing, and tank mixing for controlling blight in chickpea

Non-Peer ReviewedTotal crop losses can result from ascochyta blight on chickpea (caused by Ascochyta rabiei). A study was conducted to investigate effective fungicide application strategies in particular fungicide application timing as well as product choices, sequencing and mixtures for blight control. In addition, this study is expected to provide information on resistance management through fungicide rotations, mixtures or sequences. Fungicide trials were conducted in Saskatoon and Swift Current using Bravo 500, Quadris, Headline, BAS510 and Dithane in various sequences or tank mixes on cultivars Myles and CDC Yuma. Only Bravo 500 is registered on chickpea. Quadris had emergency registration in 2002. Applications were timed at the seedling stage, pre-flower, early-flower, late-flower and the podding stages. These results relate to the trial at Swift Current. Cultivar CDC Yuma developed higher infection levels than Myles. The level of disease control by each fungicide treatment was dependent on cultivar. The above average rainfall in Swift Current increased the level of blight severity and consequently it required several sprays especially on cultivar CDC Yuma to protect the crop. Cool wet weather towards the end of the season also delayed maturity and affected yield and seed quality. Disease severity was 97% and 82% in the untreated plots of CDC Yuma and Myles, respectively. In treated plots, it ranged from 13-50% in Myles and 15-96% in CDC Yuma. The yields varied from 434 to1956 kg/ha for CDC Yuma and 1430 to 2627 kg/ha for Myles. When spraying started before symptoms (per calender sprays with five applications), the high rate of Dithane at 2.44 kg a.i./ha reduced disease severity and increased yield more than the low rate of Dithane at 1.68kg a.i./ha. Sequencing Headline and Dithane in the per calender spray was better than per calender sprays with Dithane alone on both cultivars. However, per calender spray with a high rate of Dithane alone compared well with some treatments which included Headline or Quadris on Myles. Almost all other sequences were effective on Myles, but on CDC Yuma the most effective were those that included mostly Headline and in some cases Quadris. In general, at least three sprays to Myles and most treatments with at least four sprays to CDC Yuma reduced blight to less than 50% and also increased yields by up to 84% in Myles and up to 351% in CDC Yuma. The results suggest that there could be a range of different fungicides and sequences one might use to adequately protect chickpea, but this will depend on the registration of products other than Bravo 500

Fungicide application timing for management of Ascochyta blight in chickpea

Non-Peer ReviewedAscochyta blight of chickpea [Ascochyta rabiei] is an extremely destructive disease capable of causing high yield and quality losses. The disease is widespread in chickpea growing areas of the prairies, and the pathogen can survive in crop debris for several years. Although partially resistant cultivars are available, the disease can still be devastating if weather conditions are favourable, making fungicides an important disease management tool. Trials investigating the effectiveness of different fungicide application timings and sequences were conducted on the desi cv. Myles and the kabuli cv. CDC Yuma at Saskatoon in 2003. The products used included Bravo 500, Headline, and Lance. The first application was made prior to flowering, when disease pressure was still extremely low. Additional applications were made at early flower, mid-flower, late flower or podding, with a maximum of three applications per treatment. In both cultivars, treatments without a pre-flower application of fungicide had higher disease severity and lower yields than treatments with a pre-flower application. Treatments without a pre-flower application that were sprayed three times were still inferior to treatments with a pre-flower application that were only sprayed twice. These results emphasize the need for early and frequent scouting for disease symptoms in chickpea to allow for early fungicide application if it is appropriate

Disease management strategies for Ascochyta blight of chickpea

Non-Peer ReviewedManagement of chickpea ascochyta blight is a difficult task that requires ongoing attention and utilization of all possible techniques. Starting with clean seed of a resistant cultivar is critical, but even with this sound foundation, fungicide application is often necessary. Optimizing fungicide application strategies in chickpea is essential to protect the crop while simultaneously keeping costs as low as possible. Field experiments showed that early application of fungicide is crucial, and often additional applications were necessary for effective disease management. Of the product sequences tested, those including two strobilurin applications and two other applications during the season gave superior disease control in several cases, but this did not always confer higher yields. Nozzle type had no effect on disease development or yield in any of the field site-years. Similarly in the laboratory study, nozzle types had no effect on the amount of spray coverage or the degree of spray penetration into the crop canopy. A similar laboratory study comparing carrier volumes showed that using a higher carrier volume (>100 L ha-1) improves penetration of a fern leaf-type canopy, but offered no benefit in a unifoliate canopy. In the field, increasing carrier volume did not improve disease control when disease pressure was low to moderate. In some cases under high disease pressure, higher carrier volumes were important for achieving disease control

Genetic improvement of chickpea for western Canada

Non-Peer ReviewedThe chickpea crop has experienced a roller-coaster ride over the past decade in western Canada. Production rose rapidly in the late 1990’s, followed by dramatic declines in the past two years. Instability can be attributed to many factors including commodity prices, erratic weather patterns, Ascochyta blight and late maturity. This paper summarizes current research on genetic improvement of chickpea at the University of Saskatchewan, with particular emphasis on efforts to improve Ascochyta blight resistance and to develop varieties with earlier maturity. Under ‘average’ weather conditions, chickpea remains an excellent nitrogen-fixing crop for the Brown and Dark Brown soil zones

Effect of HIV self-testing on the number of sexual partners among female sex workers in Zambia: A randomized controlled trial

Objectives: To assess the effect of two health system approaches to distribute HIV selftests on the number of female sex workers’ client and nonclient sexual partners. Design: Cluster randomized controlled trial. Methods: Peer educators recruited 965 participants. Peer educator–participant groups were randomized 1 : 1 : 1 to one of three arms: delivery of HIV self-tests directly from a peer educator, free facility-based delivery of HIV self-tests in exchange for coupons, or referral to standard-of-care HIV testing. Participants in all three arms completed four peer educator intervention sessions, which included counseling and condom distribution. Participants were asked the average number of client partners they had per night at baseline, 1 and 4 months, and the number of nonclient partners they had in the past 12 months (at baseline) and in the past month (at 1 month and 4 months). Results: At 4 months, participants reported significantly fewer clients per night in the direct delivery arm (mean difference 0.78 clients, 95% CI 1.28 to 0.28, P ¼ 0.002) and the coupon arm (0.71, 95% CI 1.21 to 0.21, P ¼ 0.005) compared with standard of care. Similarly, they reported fewer nonclient partners in the direct delivery arm (3.19, 95% CI 5.18 to 1.21, P ¼ 0.002) and in the coupon arm (1.84, 95% CI 3.81 to 0.14, P ¼ 0.07) arm compared with standard of care. Conclusion: Expansion of HIV self-testing may have positive behavioral effects enhancing other HIV prevention efforts among female sex workers in Zambia. Trial Registration: ClinicalTrials.gov NCT02827240. Copyrigh

Contraceptive use and unplanned pregnancy among female sex workers in Zambia☆☆☆★

Objectives: Access to reproductive healthcare, including contraceptive services, is an essential component of comprehensive healthcare for female sex workers (FSW). Here, we evaluated the prevalence of and factors associated with contraceptive use, unplanned pregnancy, and pregnancy termination among FSW in three transit towns in Zambia. Study design Data arose from the baseline quantitative survey from a randomized controlled trial of HIV self-testing among FSW. Eligible participants were 18 years of age or older, exchanged sex for money or goods at least once in the past month, and were HIV-uninfected or status unknown without recent HIV testing (<3 months). Logistic regression models were used to assess factors associated with contraceptive use and unplanned pregnancy. Results: Of 946 women eligible for this analysis, 84.1% had been pregnant at least once, and among those 61.6% had an unplanned pregnancy, and 47.7% had a terminated pregnancy. Incarceration was associated with decreased odds of dual contraception use (aOR=0.46, 95% CI 0.32–0.67) and increased odds of unplanned pregnancy (aOR=1.75, 95% CI 1.56–1.97). Condom availability at work was associated with increased odds of using condoms only for contraception (aOR=1.74, 95% CI 1.21–2.51) and decreased odds of unplanned pregnancy (aOR=0.63, 95% CI 0.61–0.64). Conclusions: FSW in this setting have large unmet reproductive health needs. Structural interventions, such as increasing condom availability in workplaces, may be useful for reducing the burden of unplanned pregnancy

The influence of interviewers on survey responses among female sex workers in Zambia

Background: Interviewers can substantially affect self-reported data. This may be due to random variation in interviewers’ ability to put respondents at ease or in how they frame questions. It may also be due to systematic differences such as social distance between interviewer and respondent (e.g., by age, gender, ethnicity) or different perceptions of what interviewers consider socially desirable responses. Exploration of such variation is limited, especially in stigmatized populations. Methods: We analyzed data from a randomized controlled trial of HIV self-testing amongst 965 female sex workers (FSWs) in Zambian towns. In the trial, 16 interviewers were randomly assigned to respondents. We used hierarchical regression models to examine how interviewers may both affect responses on more and less sensitive topics, and confound associations between key risk factors and HIV self-test use. Results: Model variance (ICC) at the interviewer level was over 15% for most topics. ICC was lower for socio-demographic and cognitively simple questions, and highest for sexual behaviour, substance use, violence and psychosocial wellbeing questions. Respondents reported significantly lower socioeconomic status and more sex-work related violence to female interviewers. Not accounting for interviewer identity in regressions predicting HIV self-test behaviour led to coefficients moving from non-significant to significant. Conclusions We found substantial interviewer-level effects for prevalence and associational outcomes among Zambian FSWs, particularly for sensitive questions. Our findings highlight the importance of careful training and response monitoring to minimize inter-interviewer variation, of considering social distance when selecting interviewers and of evaluating whether interviewers are driving key findings in self-reported data. Trial registration: clinicaltrials.gov; NCT02827240. Registered 11 July 2016

HIV self-testing among female sex workers in Zambia: A cluster randomized controlled trial

Background: HIV self-testing (HIVST) may play a role in addressing gaps in HIV testing coverage and as an entry point for HIV prevention services. We conducted a cluster randomized trial of 2 HIVST distribution mechanisms compared to the standard of care among female sex workers (FSWs) in Zambia. Methods and findings Trained peer educators in Kapiri Mposhi, Chirundu, and Livingstone, Zambia, each recruited 6 FSW participants. Peer educator–FSW groups were randomized to 1 of 3 arms: (1) delivery (direct distribution of an oral HIVST from the peer educator), (2) coupon (a coupon for collection of an oral HIVST from a health clinic/pharmacy), or (3) standard-of-care HIV testing. Participants in the 2 HIVST arms received 2 kits: 1 at baseline and 1 at 10 weeks. The primary outcome was any self-reported HIV testing in the past month at the 1- and 4-month visits, as HIVST can replace other types of HIV testing. Secondary outcomes included linkage to care, HIVST use in the HIVST arms, and adverse events. Participants completed questionnaires at 1 and 4 months following peer educator interventions. In all, 965 participants were enrolled between September 16 and October 12, 2016 (delivery, N = 316; coupon, N = 329; standard of care, N = 320); 20% had never tested for HIV. Overall HIV testing at 1 month was 94.9% in the delivery arm, 84.4% in the coupon arm, and 88.5% in the standard-of-care arm (delivery versus standard of care risk ratio [RR] = 1.07, 95% CI 0.99–1.15, P = 0.10; coupon versus standard of care RR = 0.95, 95% CI 0.86–1.05, P = 0.29; delivery versus coupon RR = 1.13, 95% CI 1.04–1.22, P = 0.005). Four-month rates were 84.1% for the delivery arm, 79.8% for the coupon arm, and 75.1% for the standard-of-care arm (delivery versus standard of care RR = 1.11, 95% CI 0.98–1.27, P = 0.11; coupon versus standard of care RR = 1.06, 95% CI 0.92–1.22, P = 0.42; delivery versus coupon RR = 1.05, 95% CI 0.94–1.18, P = 0.40). At 1 month, the majority of HIV tests were self-tests (88.4%). HIV self-test use was higher in the delivery arm compared to the coupon arm (RR = 1.14, 95% CI 1.05–1.23, P = 0.001) at 1 month, but there was no difference at 4 months. Among participants reporting a positive HIV test at 1 (N = 144) and 4 months (N = 235), linkage to care was non-significantly lower in the 2 HIVST arms compared to the standard-of-care arm. There were 4 instances of intimate partner violence related to study participation, 3 of which were related to HIV self-test use. Limitations include the self-reported nature of study outcomes and overall high uptake of HIV testing. Conclusions: In this study among FSWs in Zambia, we found that HIVST was acceptable and accessible. However, HIVST may not substantially increase HIV cascade progression in contexts where overall testing and linkage are already high. Trial registration ClinicalTrials.gov NCT0282724

Root-hair endophyte stacking in finger millet creates a physicochemical barrier to trap the fungal pathogen Fusarium graminearum

The ancient African crop, finger millet, has broad resistance to pathogens including the toxigenic fungus Fusarium graminearum. Here, we report the discovery of a novel plant defence mechanism resulting from an unusual symbiosis between finger millet and a root-inhabiting bacterial endophyte, M6 (Enterobacter sp.). Seed-coated M6 swarms towards root-invading Fusarium and is associated with the growth of root hairs, which then bend parallel to the root axis, subsequently forming biofilm-mediated microcolonies, resulting in a remarkable, multilayer root-hair endophyte stack (RHESt). The RHESt results in a physical barrier that prevents entry and/or traps F. graminearum, which is then killed. M6 thus creates its own specialized killing microhabitat. Tn5-mutagenesis shows that M6 killing requires c-di-GMP-dependent signalling, diverse fungicides and resistance to a Fusarium-derived antibiotic. Further molecular evidence suggests long-term host-endophyte-pathogen co-evolution. The end result of this remarkable symbiosis is reduced deoxynivalenol mycotoxin, potentially benefiting millions of subsistence farmers and livestock. Further results suggest that the anti-Fusarium activity of M6 may be transferable to maize and wheat. RHESt demonstrates the value of exploring ancient, orphan crop microbiomes