Integrated pest management in faba bean

Successful production of faba bean crops in the presence of a wide range of disease-causing fungi, parasitic weeds, nematodes, insects, mites and other pests depends on the integration of genetic resistance, hygienic management, monitoring of the target organisms and timely application of appropriate chemical and biological treatments.

This paper reviews the progress in this area.Arthropod management is still overly reliant on broad-spectrum insecticides for many pests, particularly aphids, but field assessment, tillage, sowing date, plant density and weed control can minimize pest incursions. Crop assessments, bait and pheromone traps and economic thresholds are used to predict and monitor arthropod pest populations, and biological measures (natural enemy conservation and bioinsecticides) and selective chemicals (less harmful to beneficial insects) are also used.

Crop hygiene and seed bank demise is critical for management of broomrape, as much of its damage is done before the parasite is visible above ground. Mild herbicide treatments can prevent ripening of broomrape seeds with minimal damage to the faba bean crop. The main diseases caused by fungi, namely rust, ascochyta blight, chocolate spot and downy mildew, all spread rapidly when weather conditions are appropriate.

Since these weather conditions are well characterized for each disease, it is possible to intervene strategically by treating with fungicide at times of high risk. Good sources of resistance are available to the key diseases, although few current cultivars are resistant to more than one disease. Root-lesion, stem and root-knot nematodes can cause severe yield losses but several cultivars and breeding lines of faba bean have good resistance to root-lesion nematodes and at least one has resistance to stem nematode and one to root-knot nematode.

These groups of nematode species have broad host spectra so attention to rotations is particularly important. Chemical control of nematodes is difficult and biological control is still experimental. Control of the pathogenic fungi and nematodes requires that clean, non-infested seed be used and that the new crop does not get infected from debris and volunteer from the previous crop or adjacent fields.

In the presence of continued selection pressure on the pathogens and pests, continued breeding for novel resistance genes, development of new selective chemicals, screening for new biocontrol agents and the design of new management strategies will all be necessary.