Crop Watch July 2021

Early season Ascochyta blight reported in lentils

Ascochyta blight (AB) infection has been recorded on a number of PBA Hurricane XT volunteers and PBA Hallmark XT crops and volunteer seedlings at high levels even at this early part of the season on the Yorke Peninsula and in the Mid-North.

Crops should be closely monitored and if disease is severe then mid-season fungicide sprays may be required to control the infection.

Annual isolate testing

Annual controlled environment testing using AB isolates collected from South Australian commercial crops and field trials in 2020 has shown PBA Hurricane XT, currently rated MRMS to Hurricane-virulent pathotype 2 isolates, can be infected at moderate to high levels.

11 of 35 isolates were able to infect PBA Highland XT at a mostly low level.

PBA Highland XT is currently rated MR to both pathotype 1 Nipper-virulent and pathotype 2 Hurricane-virulent isolates.

This indicates that isolates that can overcome the resistance in PBA Highland XT are present in the pathogen population and may become selected for over time in farming systems where lentils are cropped intensively and under close rotation.

Table 1. 35 Ascochyta lentis isolates collected in 2020 were inoculated onto a lentil host differential set in controlled environment conditions in 2021. Entries in the table are the number of isolates per category.

Note:

• R = resistant
• MR = moderately resistant
• MRMS = moderately resistant-moderately susceptible
• MS = moderately susceptible
• S = susceptible.

Shading represents 20% or more of isolates tested causing that reaction type on the cultivar/line.

Management advice

AB is driven by rainfall, and disease will spread and become more severe with each rain event.

If in-crop seedlings are showing moderate to high levels of disease, a mid-season fungicide spray, timed ahead of rain events, may be required.

Note that AB disease will not spread during dry periods and fungicides can be held off while there is no rain.

If disease is present and rainfall is imminent, a fungicide application may be required at podding to protect the developing grain.

It is recommended that crops of PBA Hallmark XT, PBA Hurricane XT and PBA Highland XT are closely monitored during the season for any signs of disease.

Send us your pulse, canola and cereal crop disease samples

SARDI is seeking diseased samples from this year’s commercial pulse, canola, barley and oat crops. The samples will assist research scientists Sara Blake and Tara Garrard with monitoring the nature and extent of disease in 2021.

Grain growers and advisers are being asked to help in providing samples of:

• ascochyta blight in lentil, faba bean and chickpea
• Sclerotinia in pulse and canola crops
• net form net blotch and scald in barley
• Septoria in oats.

These samples will contribute to GRDC project investments that screen for any changes in ascochyta blight disease resistance of current cultivars, to monitor pathogen population changes and to also understand how serious a disease sclerotinia is for the southern pulse industry.

The barley disease samples will contribute to a national GRDC survey pathotyping key barley foliar pathogens to monitor pathogen population changes and to screen for any disease resistance changes.

Oat Septoria samples will contribute to a GRDC project identifying novel sources of oat Septoria resistance and understanding the virulence of the pathogen.

Collection kits with return envelopes will be provided to growers and advisers willing to provide samples.

For ascochyta and sclerotinia in pulses and canola, please contact:

Sara Blake
Phone: (08) 8429 2248
Email: sara.blake@sa.gov.au

For net form net blotch and scald in barley, and Septoria in oats, please contact:

Tara Garrard
Phone: (08) 8429 2247
Email: tara.garrard@sa.gov.au

Webinar: What's that symptom? Know your cereal and crop diseases

SARDI cereal and pulse pathologists will deliver a free webinar on how to diagnose and predict cereal and pulse diseases to assist with timely disease management decisions.

The webinar will also summarise the results of the  GRDC-funded 2020 SA cereal and pulse disease surveillance project

The webinar will be on held on 10 August at 10 am.

The webinar, which is part of a national disease surveillance program funded by GRDC, will provide growers with insights into what disease issues they should look out for in 2021.

Growers and agronomists will also receive relevant and timely information about seasonal disease risks to support disease management strategies.

Attendees will have the opportunity to ask any questions they may have.

Register now

Attendance to this event is free.

Register online by Friday 6 August 2021.