La reproduction du nématode des lésions racinaires Pratylenchus penetrans a été évaluée en serre sur 12 cultures de rotation. La moutarde brune (Brassica juncea) a été la meilleure plante hôte et a augmenté de 17,2 fois la population initiale. Le soja (Glycine max), le millet japonais (Echinochloa frumentacea), le colza (B. napus), le sarrasin (Fagopyrum esculentum), la moutarde blanche (B. hirta), et le raygrass vivace (Lolium perenne) ont été également très efficaces à multiplier le nématode et n'étaient pas significativement différents du seigle (Secale cereale), une plante hôte standard favorable. Le millet d'Italie (Setaria italica), l'avoine (Avena sativa), le maïs (Zea mays), et le brome des prés (Bromus inermis) ont accru respectivement de 5,8, 5,7, 4,5 et 3,2 fois la population initiale mais de façon significativement moindre que le seigle. Le millet perlé fourrager (Pennisetum glaucum) a présenté le plus faible taux de multiplication, soit 0,4. Ces résultats nous indiquent que les cultures de rotation couramment recommandées sont favorables à l'accroissement des populations du P. penetrans dans le sol à l'exception du millet perlé fourrager. Cette culture annuelle a un bon potentiel comme culture de rotation dans la répression des populations du nématode des lésions racinaires au Québec.The reproduction of the root-lesion nematode Pratylenchus penetrans was assessed on 12 rotation crops under greenhouse conditions. Brown mustard (Brassica juncea) was the best host and increased the initial population by 17.2 times. Soybean (Glycine max), Japanese millet (Echinochloa frumentacea), rape (B. napus), buckwheat (Fagopyrum esculentum), white mustard (B. hirta), and perennial ryegrass (Lolium perenne) were also very efficient in multiplying the nematode and were not significantly different from rye (Secale cereale), a standard host crop. Foxtail millet (Setaria italica), oats (Avena sativa), corn (Zea mays), and bromegrass (Bromus inermis) increased the initial population by 5.8, 5.7, 4.5, and 3.2 times respectively, but significantly less than rye. Forage pearl millet (Pennisetum glaucum) was the poorest host with a reproduction rate of 0.4. These results indicate that most commonly recommended rotation crops are suitable for the build up of P. penetrans populations in the soil with the exception of forage pearl millet. This annual crop has a great potential as a rotation crop for controlling the root-lesion nematode in Quebec

Various crops were evaluated in 3-year rotation sequences for their ability to reduce population densities of the potato root-lesion nematode, Pratylenchus penetrans, and improve subsequent potato (Solanum tuberosum) yield in field microplots. Forage and grain pearl millets (Pennisetum glaucum) were evaluated against oats (Avena sativa), Indian mustard (Brassica juncea), soybean (Glycine max), rye (Secale cereale), potato, and corn (Zea mays). Population densities of P. penetrans were high under rye, potato, oats, and Indian mustard and low under both forage and grain pearl millets. A single year of grain pearl millet after two consecutive years of potato or rye significantly reduced P. penetrans populations compared with 3 years of potato or rye and two consecutive years of corn, Indian mustard, oats, or soybean. One year of forage or grain pearl millet prior to potato decreased P. penetrans populations below the damage threshold of 1000 kg -1 of soil. The subsequent potato crop produced the highest marketable and total yields following either three consecutive crops of forage or grain pearl millet or a single crop of forage or grain pearl millet preceded by rye or soybean. Total yields of potato 'Superior' were significantly negatively correlated with soil densities of P. penetrans in both fall 2002 (P < 0.001, r = -0.539) and spring 2003 (P < 0.001, r = -0.423). Both forage pearl millet 'CFPM 101' and the grain pearl millet hybrid 'CGPM H-1' have potential for the magagement of P. penetrans in Quebec's potato-production system.

Two 1-year rotation experiments were conducted from 1998 to 2000 to assess the impact of forage and grain pearl millet (Pennisetum glaucum) on Pratylenchus penetrans populations in a tobacco field (Nicotiana tabacum cv. Delgold) in Quebec. Performance of these crops was compared with rye, the standard rotation crop. Rye plots were doubled to include a fumigated standard (application of metham sodium at 67.4 liters/ha on a band). Forage pearl millet increased tobacco yields by an average of 103% compared with nonfumigated rye. In 2000, leaf dry weights of tobacco following grain pearl millet CGPM H5 and CGPM H6 was increased by 70 and 73%, respectively, when compared with nonfumigated rye and were not significantly different from the fumigated plots following rye. Forage and grain pearl millet should be considered as a viable alternative to fumigation for controlling P. penetrans infestation in flue-cured tobacco production in Quebec.

The stem and bulb nematode, Ditylenchus dipsaci, is a plant-parasitic nematode affecting over 500 plant species worldwide. Since 2012, garlic producers from Ontario and Quebec have been particularly affected with economic losses caused by this pest. Reproduction of D. dipsaci on a particular host depends on its biological race, and races are unknown for these populations from eastern Canada. As a polyphagous pest, D. dipsaci can possibly be a threat and have negative impact on many crops grown in Quebec, such as field and vegetable crops (e.g., onion). In this study, the host range of four populations of D. dipsaci from Quebec and Ontario was determined in a greenhouse experiment using 11 crops. Garlic, onion, and green onion showed high susceptibility to the nematode, whereas reproduction on potato was poor. No reproduction was observed on corn, soybean, barley, alfalfa, mustard, carrot, and lettuce. These crops could therefore be used as rotational crops in a control program. Thirty-two populations of D. dipsaci were also genetically characterized using genotyping-by-sequencing. The comparison of allele frequencies at 481 loci showed that most of the populations had a genotype similar to a reference population from northern Ontario. However, a sample from eastern Quebec exhibited a distinct genotype and will require further phenotyping in a greenhouse to preclude the possibility of a different race.

Un inventaire des nématodes phytoparasites et entomopathogènes présents dans des vignobles du Québec a été réalisé dans les régions de l’Estrie et de la Montérégie, les deux principales régions productrices de vignes. Des échantillons de sol provenant de 13 vignobles ont été analysés pour la présence de nématodes phytoparasites et entomopathogènes. Six genres de nématodes phytoparasites ont été observés. Les genres les plus fréquemment retrouvés étaient Pratylenchus et Paratylenchus, lesquels ont été observés dans 85 % des échantillons de sol. Aucun spécimen du genre Xiphinema n’a été retrouvé dans les vignobles. La présence de nématodes entomopathogènes fut notée dans 85 % des vignobles échantillonnés. Des nématodes entomopathogènes de la famille des Steinernematidae ont été observés dans 11 vignobles et des Heterorhabditidae dans un seul vignoble. Tous les isolats de Steinermatidae ont été identifiés comme étant de l’espèce Steinernema carpocapsae.A survey of plant-parasitic and entomopathogenic nematodes associated with vineyards was undertaken in the Estrie and Montérégie regions, the two major grapevine-producing areas in Quebec. Soil samples from 13 sampled vineyards were analyzed for the occurrence of plant-parasitic and entomopathogenic nematodes. Six genera of plant-parasitic nematodes were observed. The most commonly encountered plant-parasitic nematode genera were Pratylenchus and Paratylenchus, both occurring in 85% of sampled vineyards. No Xiphinema sp. were observed in surveyed vineyards. Entomopathogenic nematodes were recovered from 85% of the samples. Heterorhabditid and steinernematid nematodes were isolated from one and 11 vineyards respectively. Steinernematid isolates were identified as Steinernema carpocapsae