Australian Mungbean Association
Australian-grown mungbeans have quality written all over them!
Making difficult decisions about timing desiccation and harvest
Some recently harvested mungbeans have been docked due to the presence of wrinkled seed coats.
25 April, 2017
It certainly has turned cool in many areas and, as a consequence, mungbean crop development has slowed down. This is in stark contrast to the conditions in March where high temperatures were driving crop development at breakneck speed.
With the change in heat units also comes a change to decision making about desiccation and harvest time, which should stretch out more than was required in March. Although the rule of thumb is usually to harvest 7–10 days after a desiccation spray of glyphosate or immediately after a Reglone sprayout, these general parameters take no account of day degrees [heat units], residual nitrogen levels or soil moisture.
Marketers have been reporting that they are receiving too many loads of recently harvested mungbeans that have a wrinkled seed coat or with some of the beans still soft and squishy. Such loads may incur dockage of $100.00 per tonne or more. Perhaps the rush to desiccate and then harvest has been 3–5 days too early in many fields.
The indeterminate flowering habit of mungbeans and the dry conditions followed by significant rain this season means that crops can have black pods, brown pods, light green pods and small dark green pods, plus flowers all at once, makes the timing of these operations very difficult to judge.
Staining is another issue and is a result of green or sappy plant parts, or weeds, ending up in the sample and transferring sap or moisture onto newly harvested mungbean seed.
So what is the best plan for agronomists and farmers to follow? In terms of desiccation, we are still looking for 90% maturity levels. Spend some paddock time ascertaining the physiological maturity of the pods. Gently split open a pod and turn it upside down. If all the seeds fall out then that pod, no matter what colour it is on the outside, is physiologically mature.
Unevenness of maturity is a significant challenge and there is no easy formulae for hurrying up those immature pods. If physiological maturity is less than 90% then a pre-harvest spray of glyphosate will stop the development of those later pods, which then turn rubbery and get thrown out the back of the header. Experienced header operators will set the header up to eliminate as many immature pods as possible.
There are several options with different desiccants and different timings so give them consideration before going ahead. It is well worth trying a small area with your header and getting a good representative sample to your favourite marketer for their opinion. Marketers are the ones making decisions about quality and the dollars offered. Many of them have had years and years of experience exporting mungbean.
While some decision making is difficult this season, there have been many other years of dry/hot weather with late rain events where growers gained valuable experience. So, ask questions, leave plenty of footprints in your paddock of very valuable mungbeans and avoid any MRL problems by obeying the WHP of any product used.
Contact Paul McIntosh Pulse Australia, Industry Development Manager–Northern Ph: 0429 566 198