Minimising snail contamination at a snail's pace
There are several ways growers can minimise snail contamination in crops by planning to harvest when snails are not active or by baiting or burning after harvest.
Minimising contamination at harvest
If snails are present in a crop at harvest time the only way growers can avoid contaminating the grain, is to harvest when snails are low in the crop canopy and not in the grain heads.
Research, as part of the Boosting Grains Research and Development program, has found that snails actively move from 6pm at night and during cooler, overcast weather. During these times snails are more likely to climb up the stem of a plant to the head.
The best time to harvest to avoid snails in grain is from 11am to 6pm. During this time snails were found not to move and higher numbers were located under stubble.
It can be difficult to remove snails once they are present in grain, especially if the snails are the same size as the grain.
Small scale trials have shown that drying the grain in a grain dryer will not kill snails.
Minimising snail contamination after harvest
After harvest there are options for snail control.
Windrow burning can be effective. In 2015 Department of Primary Industries and Regional Development (DPIRD) trials, initiated by the Grain and Research Development Corporation’s (GRDC) Albany Regional Cropping Solutions Networks (RCSN) group, found that burning the windrow led to a significant reduction in snail populations.
In a windrowed canola paddock with standing stubble next to the windrows, the highest proportion of snails was in the windrow - at more than 200 per square metre.
Baiting after harvest is possible to kill snails but needs to be done only if snails are actively feeding.
Snails will move during summer if there is sufficient moisture but this does not mean the snails are actively feeding.
Small conical snails and round snails won’t lay eggs until Autumn.
Place a small amount of baits to determine if snails are actively feeding before baiting an entire paddock.
Trials funded by GRDC,in conjunction with the Stirlings to Coast Farmers, found that if baits are evenly spread, small conical snails are more likely to encounter them.
Getting an even bait spread can be difficult.
SnapBait app for Smartphone
SnapBait, an app produced with funding from Boosting Grains Research and Development program, has been designed to assist with bait spreader calibrations.
The app detects blue or green baits on an even background such as gravel, bitumen, concrete or level bare ground onto which the baits should be spread for calibration purposes.
SnapBait is available for Android and iPhone, and is very easy to use:
- Take a photo at knee-height or pick one from the gallery
- Let the app detect and count the baits
- The app will then give an estimate density of baits per square metre.
A standard size card (e.g. credit card) is required to be placed within the photo for the phone to have a reference of the bait size. This will give spread per square metre.
DPIRD recommends taking more than one photograph along a transect. Each photo and result may be saved with date, time, GPS coordinates and you can label or add notes to each result.
For more information contact Svetlana Micic, research officer, Albany on +61 (0)8 9892 8591.