Wheat is the world’s third most-produced cereal grain, and grown on more land area than any other farmed foodstuff. It’s second only to rice as the main human food crop. Barley, rye and triticale are other commercially important cereals susceptible to slug damage.
Susceptibility to Slug Damage
Of the three main arable crops susceptible to slug damage, wheat is the one most likely to be damaged at the seed stage. Moving through the seedbed soil, slugs will likely attack seeds as soon as they’ve been drilled. The seed-hollowing so characteristic of slug attack is caused by the slug seeking out the seed’s embryo and endosperm.
A single slug can attack as many as 50 wheat seeds in the week after drilling.
It is not just the seeds that they attack, either. Young cereal leaves are particularly attractive to slugs – shredding being the most obvious sign. Unlike oilseed rape seedlings, which have their growing points above ground, cereals’ growing points are below ground and so will only be compromised if seeds are sown into an unconsolidated seedbed. Grazing damage to cereal seedlings is rarely disastrous; plants will usually recover after treatment with pellets.
Species of Concern
The grey field slug, Deroceras reticulatum, is the most common pest of cereal crops although both the keeled and round-backed slugs also cause damage.
Symptoms of Attack
Shredding of young leaves and stems. In severe cases areas of attack whole plants and parts of fields will be cleared.
Broadcasting pellets usually gives the best results – they are found more readily. If the seedbed is as fine and firm as it should be, then admixed pellets will not be found by the slugs! If trapping has revealed slug populations below the threshold level – four or more in a trap – then it’s wise to keep monitoring for problems, especially if conditions deteriorate or establishment is slow. An even distribution is important to ensure slugs come into contact with pellets as soon as possible. Calibrate your equipment carefully. Cultural Control methods can help reduce the need for slug pellets.