oil to neighbouring plants, creating patches of blighted and dying plants in the field. When seedlings infected with BGM are pulled up, grey mycelium can often be found on the stems just under the soil.
The fungus that causes botrytis grey mould is always present to some extent on pulse crop residues, especially from chickpea, faba bean and vetch. Airborne spores released from old infected crop residues early in the season can infect new crops. Grey mould can infect lentil at any time during the growing season, but epidemics generally develop late, after the plant canopy has closed. Periods of high humidity in spring favour rapid development of the disease. The fungus may establish a foothold on senesced plant parts, or on tissues damaged by hail, wind or machinery. It can also attack healthy plants and has a broad host range that includes faba bean, vetch, chickpea, field pea and lucerne. Flowers and pods are particularly sensitive to botrytis grey mould infection, which reduces pod set and seed quality. After harvest, the fungus survives as mycelium on plant residues and as sclerotia in the soil to enable its long-term survival.
Prevention of BGM seedling blight begins with sowing disease-free seed. Seed treatment with thiram plus thiabendazole, or thiram alone will control most, but not all, botrytis infections.
Timing and management of crop canopy closure is important in botrytis grey mould control. Follow recommended sowing times and sowing rates for the district. Crops with excessive vegetative growth and lodging are more prone to infection and losses due to botrytis infection. Airflow through the crop canopy reduces the in-crop humidity and this reduces the severity of infection.
Apply foliar fungicides just prior to canopy closure to prevent botrytis grey mould establishing in a crop. Fungicides should be considered in crops or varieties that are more susceptible to botrytis grey mould infection.
Taller, erect varieties or slower growing varieties are at less risk of infection, irrespective of their disease rating. Lush growth or lodging that provides a humid microclimate under the crop canopy enhances the inherent variety susceptibility. PBA Jumbo2, PBA Herald XT and the supersede variety Nipper are rated resistant (R) to botrytis grey mould. Several others are rated moderately susceptible to moderately resistant (MS/MR). Other lentil varieties are moderately susceptible (MS) to BGM, but PBA Bolt and Northfield are particularly susceptible (S).
Do not grow lentil in, or adjacent to, paddocks where grey mould has recently infected chickpea or lentil, or where chocolate spot has infected faba bean.
See also 'Lentil: Integrated disease management'
Lentil crops surveyed in South Australia and Victoria commonly have Cucumber Mosaic Virus (CMV) present, a disease that can occasionally express as a major problem. Viruses do pose a threat to lentils if ignored. In unique cases where lentil crops have experienced heavy losses from viral infection, it has been in association with prolonged, high levels of aphids that arrived early. Combinations of CMV, Alfalfa Mosaic Virus (AMV) and Beet Western Yellows Virus (BWYV) are often present when lentil crops are sampled.
The most important factors that predispose pulse crops to severe virus infection are:
- close proximity to a substantial virus reservoir (e.g. lucerne, summer weeds, infected lentil seed)
- high summer-autumn rainfall and the subsequent uncontrolled multiplication of aphids on host plants.
Early aphid flights to newly emerged crops can cause economic loss as early infection has a larger impact on yield and infected plants will act as a inoculum source for further virus spread within the crop.
Lentil problem solver
- 'Lentil: Integrated disease management'
- ‘Virus management in pulses’
- Crop protection products for current permits and registrations for pulses
- Refer to individual product labels and local professional advice.
Redlegged earth mite (RLEM) (Halotydeus destructor) and blue oat mite (BOM) (Penthaleus major) can cause significant damage to young lent