21 May 2024. Paul McIntosh, Pulse Australia and WeedSmart.
There is always something in our broadacre Agriculture scene that really defies easy positive corrective action, and you just have to shake your head at times.
Just recently the Uni SQ in Toowoomba hosted a mung bean and nematode field day at long term supporters of Nematode research, the well-respected Gwynne Family farms at Jondaryan. These field days are invaluable and re-educate us all in the farming community to not forget about this sneaky below ground issue. I must give my thanks to the Centre for Crop Health team at the UniSQ.
Nematodes in general are microscopic eel like organisms that feed within plant roots and do lots of vascular damage to the root system below ground. They have unpronounceable names like Pratylenchus Thornei and P. Neglectus under the Root Lesion Nematodes (RLN) banner. Reniform is another nematode type that can markedly affect cotton crops.
The sugar industry also has their own pain with Spiral and Stubby root nematodes. These forms of below ground pests can really affect yields across a range of crops like cotton, sugar cane, wheat, grain sorghum, chickpeas, wheat, barley, and mung beans to name a few. Yield penalties can be up to 65 % where high nematode numbers are detected. By high numbers I mean of 5 to 8 Thornei nematodes per gram of soil.
The real kicker is there’s nothing really in a drum from the nematicide pesticide world that can be applied on the ground to control these below-ground pests. This unfortunately can heavily impact our crop yields. Plus, they have this very prolonged ability to survive in either our worst droughts or even extended soil saturation events.
Nematode movement and infection around your neighbourhood farming area is usually by soil particles or soil lumps containing these nematodes, being transported by overland flood waters, machinery and even your humble agronomist transport be it bike or vehicle.
So, what can we do about them? Being aware and adopting a soil testing regime with Predicta B tests is a good start. Then you know what levels are and where you may have these dratted pests. After this, plant your most tolerant or non-host crop type to drive down the numbers. Pay particular attention to varieties as some varieties enhance numbers of nematodes and other varieties reduce numbers of these critters in the soil. Keep this sort of crop rotation going for a few seasons and remember that many wheat varieties can be some our most susceptible species.
Are they a new pest like Fall Armyworm? The answer is no. However, we really do forget about these unseen eel worm-like organisms, until our crops look very unthrifty in patches. Many possibly incorrect assumptions are then made about poor nutrition, lack of PAW (plant available water), soil constraints or even residual herbicide damage.
I’m not saying these issues should be ignored; however, you should add the possibility of nematodes being in your farming systems and make some changes in your crop sequencing with nematode non-hosting varieties or species. You cannot see them or dig them up like damaging scarab grubs or wireworms, yet these pests are costing our ag community many millions of dollars in revenue, so don’t forget about them in your rush to continue other farming operations.
Image: Effects of nematodes – images from the UniSQ.