It is present in the soil and plants will take it up through the root system when they are under stress. Failure in any of these areas can lead to asparagus decline. Ph should be between 6.5 and 7.5. Add limestone if soil Ph is below 6.0. The cutworm feeds at night below the soil on one side of the spear tip.
Spears are then unmarketable.
Cutworms can be controlled using an approved insecticide. Asparagus beetles lay eggs on spears, making them unmarketable. During fern growth after harvest, they chew on stalks, stripping off the green material, causing fern dieback. Asparagus beetles are controlled with an approved insecticides. European asparagus aphids feed on fern growth, injecting a toxin.