Two new species of Paratrichodorus Siddiqi, 1974 (Nematoda : Trichodoridae) with observation on P. mirzai (Siddiqi, 1960) Siddiqi, 1974 and P. renifer Siddiqi, 1974 from Pakistan

Deux nouveaux #Paratrichodorus provenant de la rhizosphère de goyavier (#Psidium guajava), à Faisalabad, Pakistan, sont décrits et illustrés. #Paratrichodorus psidiumi n. sp. peut être aisément distingué de toutes les espèces déjà décrites par la taille plus faible du corps, des spicules et du gubernaculum, et par le nombre de pores latéraux postérieurs à la vulve. #P. faisalabadensis n. sp. diffère des autres espèces par la combinaison de caractères suivante : forme du vagin et de la sclérotisation vaginale, spicules et gubernaculum plus petits. Des précisions morphométriques et morphologiques sont données sur #Paratrichodorus mirzai (Siddiqi, 1960) Siddiqi, 1974 - vulve double - et #P. renifer Siddiqi, 1974. (Résumé d'auteur

Two new species of Paratrichodorus Siddiqi, 1974 (Nematoda : Trichodoridae) with observation on P. mirzai (Siddiqi, 1960) Siddiqi, 1974 and P. renifer Siddiqi, 1974 from Pakistan

Deux nouveaux #Paratrichodorus provenant de la rhizosphère de goyavier (#Psidium guajava), à Faisalabad, Pakistan, sont décrits et illustrés. #Paratrichodorus psidiumi n. sp. peut être aisément distingué de toutes les espèces déjà décrites par la taille plus faible du corps, des spicules et du gubernaculum, et par le nombre de pores latéraux postérieurs à la vulve. #P. faisalabadensis n. sp. diffère des autres espèces par la combinaison de caractères suivante : forme du vagin et de la sclérotisation vaginale, spicules et gubernaculum plus petits. Des précisions morphométriques et morphologiques sont données sur #Paratrichodorus mirzai (Siddiqi, 1960) Siddiqi, 1974 - vulve double - et #P. renifer Siddiqi, 1974. (Résumé d'auteur

Effect of organic amendments and solarisation on Fusarium wilt in susceptible banana plantlets, transplanted into naturally infested soil

Despite extensive research since pathogenicity was first established in 1919, no cultural or chemical control strategy has proven effective against Fusarium wilt of bananas. The efficacy of cultural control is attributed to the suppression of pathogen activity. Yet, amending naturally infested soil with aged chicken manure has been shown to enhance disease severity, without any change in the activity of the pathogen Fusarium oxysporum f. sp. cubense (Foc) in the soil. In this study, the effect of amending soil with composted sawdust, and of solarising soil, was compared with the effect of amending soil with chicken manure. Bioassays comparing the activity of Foc in the soil with the extent of invasion of banana pseudostem tissue by Foc were used to investigate why strategies targetting pathogen survival have not proven successful in controlling this disease. The enhancement of Foc invasion of the banana plantlets was reproduced with the addition of chicken manure to the naturally infested soil. However, changes in the activity of Foc in the soil were not associated with changes in the frequency of invasion of the plantlets. Invasion of banana pseudostems in the sawdust and solarisation treatments was not significantly different from invasion in the respective control treatments, despite a reduction in the activity of Foc in the sawdust-amended soil and an enhancement in the solarised soil. Moreover, the increase in Foc activity in the solarised soil recorded during the bioassays occurred despite the effectiveness of solarisation in reducing the survival of Foc in pre-colonised banana root tips buried in the soil. Changes in the frequency of invasion were associated with changes in the availability of mineral nitrogen, particularly ammonium N. These results suggest that the physiological response of banana cultivars to ammonium N may be associated with their susceptibility to Fusarium wilt. Accordingly, cultural strategies for controlling Panama disease will only be effective if they enhance the ability of the host to resist invasion

First report of Xiphinema diffusum from Pakistan

The population of Xiphinema americanum species group was detected from the soil surronding the roots of peach (Prunus persica) during a survey of plant-parasitic nematodes in Gilgit-Baltistan, Pakistan. From the results of the morphological study, the species was identified as X. diffusum. Morphometrics of X. diffusum generally agree with those of the type species and the topotype specimens. Molecular analysis of 18S rDNA of X. diffusum from Pakistan indicated two nucleotide differences and 99 % similarity with the Chinese (AM086669) and the Australian (AM086685) population of X. diffusum. Phylogenetic analysis of 18S rDNA placed the Pakistanis population close to X. diffusum from China and Australia. This species is reported for the first time from Pakista