WIDESPREAD chocolate spot infection has been discovered in a PBA Samira faba bean crop near Wittenoom Hills.
The crop had already received two applications of Mancozeb fungicides and was going to be sprayed again with MIRAVIS Star.
The infection was also found in another faba bean crop of unknown variety at nearby Neridup.
That crop had been sprayed four weeks ago with Aviator Xpro and will be sprayed again with Veritas as soon as possible.
Chocolate spot in faba beans usually appears as red-brown spots on leaves, stems and flowers but is usually not conspicuous until after the crops start flowering.
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The spots on leaves and stems enlarge and develop a grey, dead centre with a red-brown rim or margin.
Department of Primary Industries and Regional Development senior research scientist Mark Seymour said conditions in early August were conducive to chocolate spot development in the Esperance region.
"From August 7, the Esperance region experienced seven days with relative humidity continuously at 100 per cent compared to the same period in 2021 when disease pressure was much lower and only a few hours of high humidity was measured," Mr Seymour said.
"Consequently, more disease is being seen in beans, lentils, canola and cereals than most years.
"Under this pressure all varieties of faba bean are showing some chocolate spot, albeit the best rated variety PBA Amberley (MSMR) is less affected than other varieties."
Foliar sprays provide disease control even in susceptible varieties but must be applied before rain or wet periods to be effective.
