Midge are a small but potent threat on Sorghum crops. These tiny reddish-orange mosquito like flies use the flowering sorghum for reproduction, laying their eggs in the young flowers and giving their larvae to feed on the developing seed. This causes the seed to be affected by malformation by creating an indentation in the kernel which will cause the seed to become an empty shell.
To get an idea on their prevalence in your crops take a look at the spider webs and count their presence. You can also have a look at the flowers in a certain area for larvae. Midge are found in every state save for WA and will be more prevalent among un-treated sorghum types.
A few treatments have been developed including pesticides and parasitoids, however these are used primarily in control progressed infestations of adult midges before they lay their eggs. The best options for prevention to choose resistant seed varieties. These varieties are genetically adapted to resisting midge infestation.
It is important to factor in susceptibility and threshold when considering a treatment in order to know the nature and degree of the potential midge problem. In doing so you can better understand which variety and midge- resistant sorghum might be best for you. I’ve included a couple of links below with some information on how to calculate some of the important factors.
The midge rating is a scale from 1-7 (Sometimes 8) that determines the occurrence of less damage by midge to non-resistant varieties. For instance, a midge rating of 7 means that there is, on average, 7 times less damage as compared to the non-resistant variety. There are a variety of factors when considering the best sorghum option, the midge rating is just one of those factors. I’ve put together a bit of a comparison of some of the grain sorghum we have on offer at Tara Rural Supplies and Condamine Seeds and Tyres as to the midge rating.
Some Helpful Links:
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