Ken Evans

Characterisation of potato cyst nematode populations from Portugal

Populations of potato cyst nematode (PCN) were assembled from all of the potato growing regions of Portugal, either by direct sampling of fields or from cyst samples sent to the University of Coimbra for identification. When 30 or more cysts were available, isoelectric focusing of species-specific protein bands was used to identify which PCN species were present. PCN was present in 35% of a set of 226 soil samples. PCN was also identified in a larger set of 423 populations. Of the 423 populations, 83% were pure Globodera rostochiensis, 8% were pure G. pallida and 9% were mixtures of the two. PCN was found in all of the main potato growing areas but G. pallida was not detected in Coimbra, Setubal or Viana do Castelo districts.

Epidemiology and integrated control of Nacobbus aberrans on tomato in Mexico

Population densities, population fluctuations, yield loss and disease incidence caused by Nacobbus aberrans on tomato (Lycopersicon esculentum) were studied, using an epidemiological approach, in a field experiment that included three different control regimes: an integrated control (IC) scheme, which included fertilisation, nematicide (ethoprop) and chicken manure; a technical control (TC) scheme, based on the best local practices of fertilisation and use of carbofuran for nematode control; and a check treatment (AC), with no application of fertilisers or nematicide. At least three generations of N. aberrans occurred through the cropping season and the numbers of galls/plant and females/g of root through the crop season were used to define the area under a disease progress curve (AUDPC). The variables b−1 (Weibulls apparent infection rate), AUDPC and Yf (final disease incidence) indicated less crop damage under the IC scheme than under the other two schemes (TC and AC). The IC scheme resulted in increased plant height (41-49%), foliage dry weight (37-53%) and stem diameter (31-41%) compared with the TC and AC schemes. Tomato yields in IC surpassed those from TC and AC by 34 and 83%, respectively, while TC exceeded AC by 73%. The yield loss attributed to N. aberrans was 12, 29 and 83% in IC, TC and AC, respectively. The IC scheme improved commercial production by 20 and 81% in comparison to the TC and AC schemes. This was largely due to effective control of the initial inoculum density, which affects the first generation of the nematode population; control of this generation is essential for avoidance of yield loss. The first generation is completed during the period 0-60 dat (days after transplanting), i.e., during the critical stages of flowering, fruit initiation and fruit set (40, 50 and 60 dat). Data on plant performance taken every 10 days were used to derive a multiple point model for calculation of production loss.

Introduction (Historical and Overview)

Biological control is an alternative to chemical control of plant-parasitic nematodes. This is largely due to public demand for biologically-based and environment-friendly management options for safer pest control. Such demands have had an important impact on biological control research expansion and funding. However, the development of any strain of a biological control agent for nematode control requires many years of research, experimentation, validation and safe-use tests before the biological control agent becomes available to farmers or is further developed by industry as a commercial biopesticide or bionematicide. Biological control potential can be unconstrained when biological control agents are used in combination with compatible integrated pest management tactics, which may include some chemical products and other biological control agent-based products that are currently available on the biopesticide market. This chapter presents part of the history behind some of the initial studies that help to illustrate the scientific work carried out by the many scientists who laid the foundations and helped to develop Pochonia chlamydosporia as a viable, sustainable alternative to chemical control in the integrated management of plant-parasitic nematodes.