AS growers look forward to a promising mungbean season, they can be assured that a team of scientists has worked hard to understand and respond to the pest and disease issues likely to arise.
Dr Rex Williams, director of crop improvement for the Department of Agriculture and Fisheries, is overseeing and integrating the work of the department’s plant breeders, pathologists, entomologists and crop scientists who lend their expertise to the mungbean industry.
This co-ordinated and concerted effort underpins the continued growth of the mungbean industry at a time of unprecedented opportunity.
“The demand for clean, bright Australian mungbean product is high and will reward growers who take advantage of the latest knowledge and advice available to meet the new challenges that will inevitably come,” Dr Williams said.
“The plant breeding team has achieved excellent results with the release of varieties such as Crystal, Satin II, Jade AU and Celera II-AU [C1] that have established new benchmarks in yield and disease resistance. There are also new lines coming through the breeding program that will build on these advances.”
The industry’s most recently released variety, Celera II-AU, provides growers with a high level of halo blight resistance and there is good reason to expect improved halo blight resistance in varieties to be released in coming years.
With no in-crop control available to treat infected crops, Dr Williams says information about a new race of the halo blight pathogen is required to help screening of new mungbean varieties in the plant breeding program to ensure improvements that growers can depend on.
“The pathology team relies on growers and agronomists sending in suspect disease samples for diagnosis and to help build a picture of disease presence, virulence and spread,” he said.
“Any crops showing suspected symptoms of halo blight, tan spot or other diseases are of particular interest to DAF plant pathologist, Lisa Kelly.”
Powdery mildew remains an important and damaging disease in mungbeans with the potential to wipe out almost half of a crop’s potential yield under ideal conditions. The only viable options for management of powdery mildew are resistance and foliar fungicides. Crystal and Jade AU offer slightly better resistance to powdery mildew than the other varieties currently available. Other than choosing the most resistant variety, growers must be prepared to protect crops with well-timed foliar fungicides ahead of rain.
Several formulations of sulphur are either registered or under permit for management of the mungbean powdery mildew pathogen. However, the fungicide tebuconazole, currently under APVMA permit (Permit PER13979 in NSW and Queensland only) and sold as Folicur 430SC or Hornet 500SC, is superior to sulphur and has become the standard product of choice. Field trials have shown good control if the first fungicide spray is applied at the first sign of powdery mildew on the lower leaves, with a second spray being applied two weeks later.
Even if powdery mildew is not visible, good results have also been achieved with a prophylactic spray just before flowering.
As mungbean plantings have increased over the past few years, the entomology team has helped growers contend with an array of old and new pests, and pests behaving oddly – the most notable examples being etiella up to 60 per square metre in vegetative and podding mungbeans and bean podborer found west of the Great Divide.
“Determining exactly what damage these pests were doing and coming up with management packages for growers to use in response requires significant experience and expertise,” Dr Williams said.
Etiella has become a significant pest, particularly in spring planted crops. Once larvae are inside pods or stems, they are out of sight and cannot be reached with insecticides, so emphasis needs to be put on early detection of infestations in both vegetative and podding crops.
Early warning signs are damaged and dying auxiliary buds in vegetative crops and minute entry holes in pods in podding crops, as well as increasing moth activity – although the moths are very hard to catch.
Then there was the mystery planthopper that has been in large numbers in some mungbean crops but appears to do little or no economic damage to the seeds, even though pods may be stung multiple times.
“There are still many unanswered questions about the behaviour of these pests,” Dr Williams said.
“It is very useful for DAF entomologists if growers can leave an unsprayed strip when they apply insecticides and take note of the effect or otherwise of these sprays.”
DAF CALL REPORT IT!
DAF entomologists Hugh Brier and Dr Melina Miles are keen to have insect outbreaks reported to them along with information from growers about effectiveness of the treatments during the season.
In terms of crop rotations, growers are reminded that while mungbeans can tolerate root-lesion nematode (RLN), Pratylenchus thornei, RLN numbers are likely to increase in the soil.
This can be a problem in the northern region where RLN can cause yield losses as high as 70 per cent in intolerant varieties of wheat. Growers are encouraged to test their soil for RLN and
to factor this in when they are choosing wheat varieties for next winter.
The research and extension effort backing the Australian mungbean industry is an essential part of the increased confidence growers can have when they plant this quick and profitable summer pulse crop.
