Recent wet conditions have been ideal for disease development. Diseases will be best controlled using a proactive fungicide response before disease has fully developed. It is not the year to wait and see!
Stripe rust, powdery mildew, septoria and yellow leaf spot are present in wheat crops. In barley, spot form of net blotch (SFNB) is widespread and scald is starting to appear. Ascochyta blight has been reported in chickpeas, faba beans and vetch.
CEREALS
Powdery mildew in wheat
Powdery mildew is appearing in Wimmera and Mallee wheat crops, especially cv. Scepter, which is rated as SVS. Ideally this disease is controlled with a spray prior to canopy closure (~GS31), however, a spray even at full flag emergence (GS39) will still be useful and also provide protection for rust later in the season. For more information refer to the GRDC information note ‘Powdery mildew in barley and wheat’ ww.grdc.com.au/GRDC-FS-PowderyMildewBarleyWheat
Septoria in wheat
Septoria is widespread in Victorian wheat crops. In the Wimmera, a spray at early tillering is recommended if Septoria symptoms are present in the crop. In the Mallee, Septoria should be considered as part of the stripe rust and mildew control strategy. In the high rainfall zone, susceptible varieties must be protected with fungicides. Inspect crops carefully, focusing on the oldest leaves looking for lesions with black fruiting bodies present. Applying fungicides early in the epidemic will provide more effective control than letting the disease develop. To help protect fungicides from resistance developing, the same active should not be applied more than once in any crop. Ideally different fungicide groups should be applied and mixtures used. It is also important that the same active is not applied. For more information refer to the ExtensionAUS™ article ‘Protect wheat from Septoria tritici this spring’ https://extensionaus.com.au/field-crop-diseases/protect-wheat-from-septoria-tritici-this-spring
Stripe rust in wheat
Stripe rust is present in the Victorian Mallee and is expected to spread quickly during September. As this is a relatively early outbreak of stripe rust, it is recommended that all wheat crops rated as MS or worse are protected with a fungicide at ~GS39 and then monitored for further rust development. Consult the Agriculture Victoria current disease guide for variety ratings http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/plant-diseases/grains-pulsesand-cereals/cereal-disease-guide
Scald in barley
As expected, scald is starting to develop in barley crops. It is important that once scald starts to develop that a fungicide is applied soon after its detection. Agriculture Victoria research has shown that good scald control can be achieved by applying fungicides at both GS 31 and 39, or if an up-front treatment has been used (e.g. flutriafol or Systiva) a fungicide application at GS 39 provides good control. A proactive approach to scald control in susceptible varieties is warranted in Wimmera and high rainfall zone crops.
SFNB partial resistance to Systiva
There are confirmed reports of partial resistance to Systiva in SA (SARDI and CCDM). Agriculture Victoria has sent multiple samples to CCDM for testing and we will provide an update when results become available. At this stage, our recommendation is that this finding will not change the recommendation to apply a spray at GS39, given the pressure from recent conditions. Agriculture Victoria has shown that good control of SFNB can be achieved by applying foliar fungicides at both GS 31 and 39, or if Systiva was used then at GS 39.
PULSES
Ascochyta blight (AB) has been reported in a number of crops in the Wimmera and Mallee during the past few weeks, particularly in chickpeas with some reports of AB on faba beans and vetch. This is a timely reminder that even resistant pulse varieties will need monitoring as under severe disease pressure, a fungicide application may be required to control disease. Agronomists are asked to send in samples of AB on faba beans to CropSafe due to the detection of a new pathotype in Kaniva and Horsham in 2015. This pathotype has overcome the resistance in Farah making is as susceptible as Fiesta. With PBA Rana and Zahra also partially compromised. PBA Samira and Nura remain resistant to AB. Chocolate spot and Cercospora have been found throughout bean crops this year and will need to be managed accordingly. However, consider the cost benefit ratio before spraying fungicide.
