Storing mungbean planting seed
Adult bruchid (cowpea weevil) emergence hole and eggs on stored mungbean.
21 May, 2017
by Philip Burrill, Senior Development Agronomist, Postharvest Grain Protection, Department of Agriculture and Fisheries (DAF)
Monitor: At least once a month.
- At least once in four weeks, sample some mungbean seed from 25 kg bags, 1 tonne bags or bulk in silo. Keep a record of what you do or don’t find. Also record any fumigations.
- Sieve samples in insect sieve to look for cowpea weevil (bruchids) and other pests. It is a good idea to leave an insect probe trap in 1 tonne bags or bulk seed in silos to catch cowpea weevil and any other storage pests. Pull these probe traps up to inspect at the same time you sieve the grain for insect.
- Check surface of mungbean seed. The white eggs of cowpea weevils can be clearly seen fixed to the outside of seeds. Short lived adults lay about 100 eggs over 1–2 weeks, then they die. The neat round holes in seed that are made by newly emerging adults can also be easily seen.
- When making your monthly insect and seed quality check, put a grain temperature probe in to a depth of 50–100 cm level for 1 minute, then see if you are close to the 10–20 degrees C target temperature.
- Storing planting seed at lower temperature and lower moisture contents will have a direct impact on your seed germination and vigour results, especially as the storage period becomes longer (e.g. for carry over seed).
Storage and handling: Plan ahead if you usually store your own mungbean seed.
- The ideal bulk seed storage is a cone based, aerated, seal-able silo that is painted white, or is located out of direct radiant heat of the sun.
- Automatic aeration controllers will usually provide the most reliable results for cooling grain temperatures.
- If you need to move bulk seed for grading or fumigation, take care not to damage seed (e.g. running old augers half full).
Hygiene: Reduce the pest and contamination problems
- Do a thorough job of cleaning or washing out empty silos, storage sheds, augers before storing seed.
- DE dust (e.g. Dryacide®) is a product that could be used in small amounts ( 2 g/m²) as a structural treatment once an empty silo is clean of grain residues.
- Don’t contaminate a new variety or line of seed with last year’s old seed residues.
- Do not keep one or two small bags of old seed, or seed gradings, in the shed. It is likely to be a source of cowpea weevil pests that will infest your new seed.
Aeration: Keep mungbean seed cool.
- Take every opportunity to cool mungbean seed temperature down. This helps maintain germination and vigour, and reduces pest build up.
- Aim to cool mungbean seed to the temperature range of 10–20 degrees C in silos.
- Store bags and 1 tonne bags in a cool or cold location ( i.e. not in a hot shed during summer).
- Cowpea weevil life cycle is very rapid, only 3 weeks from egg to adult, when grain temperature is 30–32 degrees C.
- Good news — the population build-up of cowpea weevil is virtually stopped when grain temperature is below 20 degrees C.
Fumigation: In gas-tight, sealed enclosure.
- The key to a successful fumigation for all storage pests, including cowpea weevils, is having a gas-tight, sealed enclosure to hold the phosphine gas in the grain for a long enough time.
- Once storage pests are detected and identified from monthly checks, pressure test silo ( 10–15 minute job) to check the silo for damaged seals and air leaks, then seal up and fumigate for 10 days. Vent for 1 day, then return silo to aeration cooling. Continue to monitor for pests each month.
- Pests found in 25 kg bags or 1 tonne bags — use good quality, large, gas-proof tarp ( e.g. Darling Downs Tarpaulins, Toowoomba).
- Put large gas-proof tarp down on floor, place 25 kg bags or 1 tonne bags on tarp, then bring tarp over the top and roll up all the edges together to create a sealed enclosure.
- Before completely sealing up tarp, put standard dose of phosphine tablet on tray in an open space under tarp. Dose is 3 tablets per 2 cubic meters of volume under tarp.
- Fumigate for 10 days. Take care when removing tarp to vent. Follow label safety directions and always ensure plenty of breeze or wind blowing while removing tarp.
Germination and vigour: Test all seed.
- Important that all seed lots are tested well before potential planting opportunities.
- AgEtal in Toowoomba and NutiLab in Goondiwindi (Ph. 07 4671 5155) are two examples of seed testing labs that will provide germination and vigour test for mungbean seed.
- If you carry out your test earlier enough, then you have time to seek out another suitable source of your preferred mungbean seed variety, if your test result from the lab indicates poor germination or vigour.
Purity and seed borne diseases : Choose a reliable seed source.
- Always be careful when sourcing a new line of seed in regards risk of contamination or seed borne diseases.
- AMA seed scheme aims to minimise the risk of seed borne diseases such as tan spot and halo blight.
- Aim for varietal purity with seed lines. Be careful to clean out augers, trucks, empty silos etc if another bulk mungbean seed variety is to be stored on farm.
- Minimise the risk of introducing new weed problems to your farm.
Contact Phillip Burrill Senior Development Agronomist, Postharvest Grain Protection, DAF or Paul McIntosh Pulse Australia, Industry Development Manager–Northern Ph: 0429 566 198
Stored Grain website
Storage – Best Management Guide