Assessment of Trap Crops for The Wheat Bug, Nysius huttoni Management: A Cage Study

The wheat bug, Nysius huttoni, is an endemic New Zealand insect pest. Its feeding can seriously reduce crop establishment in forage A cage study was conducted in Lincoln University, New Zealand to evaluate the pest’s host preferences on four plant species. Kale plants (Brassica oleracea) were used as a potentially susceptible control and other four trap plants were tested to evaluate as potential trap-plants. These were: Lobularia maritima (alyssum), Triticum aestivum (wheat), Coriandrum sativum (coriander) and Trifolium repens (white clover). The alyssum plant was more attractive to the wheat bug. The survival rate and preferences of the wheat bug was significantly better than other four plants. The deployment of such flowering trap crops can potentially trap the wheat bug and also provide multiple ecosystem services (ES) in an agro-ecosystem. The findings can be used to develop the wheat bug management protocol and also potentially provide ecosystem services in brassica fields.

IDENTIFICATION OF COWPEA GENOTYPES RESISTANT TO FUSARIUM WILT1

ABSTRACT Fusarium wilt, caused by soil-borne Fusarium oxysporum f. sp. tracheiphilum (Fot), can reduce cowpea bean yield. Considering that genetic control through resistant genotypes is pivotal for Fusarium wilt control, the aim of the present study was to identify cowpea genotypes that are resistant to Fot from the Germplasm Bank of the Pernambuco Agronomic Institute, Embrapa Middle North, and other producing areas in the North and Northeast regions of Brazil. The cultivar BR-17 Gurguéia was used as a susceptible control and MNC01-649F-2-1 was used as a resistant control. Two experiments were carried out in a completely randomized design in the greenhouse of the Department of Agronomy of the University Federal Rural of Pernambuco. Plants with the first pair of expanded leaves were inoculated with a conidial suspension (106 conidia/mL) using the conidia root-immersion methodology. Fusarium wilt severity in plants was assessed 21 d after inoculation, with the aid of a descriptive scale. In the first experiment, we evaluated the resistance of 38 cowpea genotypes, of which 19 (5 moderately resistant and 14 resistant) were selected for the second experiment. In the first experiment, four genotypes (Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante) did not show any symptoms of Fusarium wilt. In the second, 15 genotypes showed high resistance to Fot, including Canapu PE and Miranda IPA 207, which again had no symptoms of Fusarium wilt. In conclusion, this study identified that the genotypes, Canapu PE, Miranda IPA 207, Esperança, and BRS Pujante have greater resistance to Fusarium wilt.

Tolerance to Virulence Phenotypes of Phytophthora capsici in Pasilla Pepper Cultivars

Phytophthora capsici is the most important limiting factor in the production of chile pepper in Mexico. This pathogen presents virulence phenotypes capable of infecting diverse cultivars of this crop. The search and development of resistance in chile pepper is an excellent alternative for the management of P. capsici. The objective of this work was to evaluate the response of four pasilla pepper cultivars to infection with five virulence phenotypes of P. capsici. Pasilla pepper landraces PAS-1, PAS-2, PAS-3, and PAS-4 were inoculated with P. capsici isolates MX-1, MX-2, MX-7, MX-8, and MX-10. Two experiments were conducted under greenhouse conditions from April through June 2017 and April through June 2018. ‘California Wonder’ was included as a susceptible control, and uninoculated plants were included as a negative control. In each experiment, groups of six 56-day-old plants from each pepper cultivar were inoculated with each virulence phenotype. Disease severity was evaluated 20 days after inoculation using an individual plant severity scale. All pepper cultivars were classified as resistant = R, moderately resistant (MR), tolerant (T), moderately tolerant (MT), or susceptible (S), according to the frequency of resistant plants (severity 0–1). ‘California Wonder’ and ‘PAS-4’ were susceptible to all five virulence phenotypes. The rest had different responses to the virulence phenotypes, but ‘PAS-2’ and ‘PAS-3’ were susceptible to only one of the five virulence phenotypes. Pasilla peppers with low severity exhibited a slow rate of infection, which is a mechanism we have called “slow wilting.” The pasilla pepper cultivars PAS-1, PAS-2, and PAS-3 could be used in plant breeding programs as sources of genetic tolerance and moderate resistance against P. capsici.

Host suitability of summer cover crops to Meloidogyne arenaria, M. enterolobii, M. incognita and M. javanica

Summary Cover crops can be a useful tool for managing plant-parasitic nematodes provided they are poor or non-hosts for the target nematode species. A glasshouse experiment was done to determine the host status of four common cover crops in Florida, sunn hemp, cowpea, sorghum sudangrass and sunflower, to pure populations of four common tropical root-knot nematode (RKN) species Meloidogyne javanica (Mj), M. incognita (Mi), M. enterolobii (Me) and M. arenaria (Ma). Tomato was included as a susceptible control. Eight weeks after nematode inoculation (WAI), tomato showed the highest root gall damage for all tested RKN species, with gall indices (GI) between 7 (Ma) and 8.5 (Me) and reproduction factor (RF) ranging from 20 (Ma) to 50 (Mj). No visible root galls were observed for any of the RKN species on sunn hemp and sorghum sudangrass at 8 WAI. However, Mj and Mi were able to reproduce slightly on sorghum sudangrass (RF = 0.02 and 0.79, respectively). Sunflower and cowpea were infected by all four tested RKN species, but host suitability varied. Sunflower root galling ranged from 1.1 (Me) to 4.5 (Mj) and RF = 3.2 (Me) to 28.7 (Mj), while cowpea root galling ranged from 0.6 (Mi) to 5.1 (Me) and RF = 0.8 (Mi) to 67.3 (Mj). Sunn hemp and, to a lesser extent, sorghum sudangrass were poor hosts to all four tested RKN species. Sunflower was a good host to all RKN species, but root gall damage and RF were lowest for Me. Cowpea was a good host to Mj, Me and Ma, but a poor host to Mi. Our results confirm and stress the importance of RKN species identification when selecting cover crops as an RKN management strategy.

Biological and Molecular Evidence for the Existence of Bruchid Ecotypes in the Nigerian Cowpea Ecosystem

The oviposition, growth and development of six populations of Callosobruchus maculatus (IT, PH, UM, MD‐1, MD‐2, MD‐3) from different localities in Nigeria were studied on a resistant (TVu 2027) and susceptible (Ife Brown) cowpea cultivar and four cultivars of African yam bean, Progenies obtained by cross‐mating individuals from the different populations were also studied.. Oviposition was highest in the MD insect beetle population and lowest in the UM population. IT and PH populations had the highest adult emergence and shortest development times on the resistant control. Genomic differences among bruchid populations were confirmed by the Random Amplified Polymorphic DNA (RAPD) fingerprinting technique with PH population being the most distant. All progenies with IT as the female parent also had better emergence and shorter development time than their reciprocal crosses or those involving other populations, but this varied with the fitness of the male parent. The UM population averaged <10% adult emergence on TVu 2027 compared to 71.9 % on the susceptible control, but was better adapted to the AYB (66 % emergence) than were other populations. These results suggest possible existence of ecotypes, of this bruchid species in Nigeria with potentially important implications for the development and deployment of resistant cowpea varieties.

Screening of sugar beet pre-breeding populations and breeding lines for resistance to Ditylenchus dipsaci penetration and reproduction

Ditylenchus dipsaci is an economically important plant-parasitic nematode affecting European sugar beets. To date, no sugar beet cultivars carrying resistance against D. dipsaci are available to farmers. To find potentially resistant sugar beet lines restricting reproduction and penetration of D. dipsaci, three consecutive in vivo bioassays were carried out. The first experiment determined the penetration rate of D. dipsaci in 79 breeding lines and 14 pre-breeding populations. Based on these results, D. dipsaci penetration and reproduction resistance of eight genotypes was intensively investigated. It could be demonstrated that none of the genotypes showed resistance towards D. dipsaci. However, a high variation of the penetration rate by D. dipsaci was observed among the genotypes. The breeding line ‘DIT_119’ effectively reduced D. dipsaci penetration (34.4 ± 8.8 nematodes/plant at 22 days post-planting) compared to the susceptible control (109.0 ± 16.9) while ensuring a yield comparable to non-inoculated plants. However, the breeding line ‘DIT_119’ did not reduce D. dipsaci reproduction. The paternal line of the cultivar BERETTA KWS, demonstrating a high tolerance to D. dipsaci crown rot symptoms, did not reduce penetration and reproduction. Thus, no correlation can be established between reduced penetration rates, reproduction, and tolerance to D. dipsaci. This study provides an essential basis for the development of resistant sugar beet cultivars to D. dipsaci. The variations observed among genotypes now need to be confirmed with larger-scale screenings.

Complete Blood Count Analysis on Beef Cattle Exposed to Fescue Toxicity and Rumen-Protected Niacin Supplementation

Offspring born to dams genetically tested for resistance to fescue toxicity were separated in groups based on their dams’ resistance level (tolerant vs. susceptible). Rumen-protected niacin (RPN) is proposed as a potential alleviator for vasoconstriction produced by fescue toxicity. Complete blood count (CBC) analysis was utilized for detection of significant responses to treatments applied. Our objectives were as follows: (a) to analyze changes in CBC due to fescue toxicity, maternal resistance level, and RPN in growing offspring; and (b) to assess the effects of maternal resistance level when consuming endophyte-infected tall fescue seeds in addition to RPN in offspring performance. Body weight, average daily gain, or health status were not improved by RPN or the genetic test to detect fescue toxicity resistance. Typical signs of alkaloids intoxication and heat stress were noticed in offspring. Particularly, rectal temperature was greater for susceptible control heifers. Results showed that susceptible control offspring presented signs of anemia denoted by low mean corpuscular hemoglobin (MCH) and mean corpuscular volume (MCV). High levels of white blood cells (WBC) and basophils in combination to low neutrophils to lymphocytes ratio were the signs of infection or inflammation detected in the CBC analysis, especially in tolerant niacin steers. Furthermore, offspring of control heifers had a greater percentage of reticulocytes and RDW, denoting signs of anemia.

Clubroot resistance in canola and brassica vegetable cultivars in Ontario, Canada

Clubroot, caused by the obligate pathogen <i>Plasmodiophora brassicae</i> Woronin, has been present on brassica vegetables in Ontario for decades, but was only recently identified on canola (<i>Brassica napus</i> L.). Once <i>P. brassicae</i> is present in a field, eradication is difficult, but resistant cultivars can provide effective management. Pathotype 6 has been the predominant pathotype on vegetable crops for decades, but pathotype 2 is predominant in canola fields in Ontario. Field trials were used to assess the reaction of selected canola and vegetable Brassica cultivars to pathotype 2, and controlled environment studies were conducted to evaluate the reaction of canola the same cultivars to pathotypes 2 and 6. Four canola cultivars with putative clubroot resistance were compared to two cultivars that were expected to be susceptible and three susceptible control cultivars. Several brassica vegetables were assessed: cabbage, cauliflower, broccoli, napa cabbage, rutabaga, and Shanghai pak choi (a susceptible control). The canola cultivars marketed as resistant were highly resistant in both the field and growth room trials. The canola cultivars not marketed as resistant were susceptible to pathotype 2, as expected. All of the canola cultivars were resistant to pathotype 6. The vegetable cultivars marketed as resistant or tolerant were resistant to pathotype 6 and most were resistant to pathotype 2. A putative resistant cultivar of cabbage and one of broccoli were resistant to pathotype 6 but susceptible to pathotype 2. Clubroot consistently reduced fresh shoot weight in susceptible cultivars of canola and brassica vegetables relative to resistant cultivars.

Response of peanut (Arachis hypogaea L.) genotypes to smut (Thecaphora frezii) in the peanut growing region of Argentina

Genetic resistance is the most efficient tool in crop disease management. Peanut smut is currently one of most important peanut diseases, with its incidence increasing in terms of both damage level and crop area covered. The aim of this study was to assess the response of different genotypes obtained by the Facultad de Agronomía y Veterinaria of the Universidad Nacional de Río Cuarto (Argentina) to smut and their yield. During the 2016/17, 2017/18 and 2018/19 crop seasons, three experimental assays were conducted in General Deheza (Córdoba province, Argentina) to evaluate the varieties Uchaima, Utré and Mapu, the advanced lines LAx-1, LAx-2, LAx-3 and LAx-4, and the cultivar Granoleico, which was used as susceptible control. Final incidence and severity of peanut smut, as well as kernel yield, were evaluated. The variety Utré and the advanced line LAx-1 exhibited the best response to smut over the three crop seasons, without differences between them, but differing significantly from the remaining genotypes. Both genotypes showed incidence below 6.8% and severity below 0.21. In the 2016/17 crop season, LAx-1 had the highest kernel yield (3791.6 kg/ha). In the 2017/18 and 2018/19 crop seasons, Utré had the highest yield (1065 and 3975 kg/ha). Kernel yield of susceptible genotypes was below 2851.6 kg/ha in the 2016/17 and 2018/19 crop seasons, and below 805 kg/ha in the 2017/18 crop season. Genotypes LAx1 and Utré are resistant to peanut smut. This is the first report of a peanut commercial variety developed in Argentina (Utré) with confirmed tolerance to smut.