Asparagus has many enemies, from insects to weeds and finally diseases. Luckily, today we have the technology and information to defend and be proactive against these threats and to also kill them if necessary.
It is especially important to control weeds since asparagus is a perennial plant and weeds are a huge threat during first years of transplanting.
One traditionally popular train of thought for controlling weeds is to use salt. According to MAAB, “This was widely practiced in the United States in the 19th century. Asparagus is tolerant to salt and most weeds are not.”
The sodium in salt can actually replace some of the plant’s potassium need and there may be some small benefit in Fusarium suppression from salt. But, it takes a lot of salt.
In one disease control study by Dr. Mary Hausbeck at Michigan State University in the 1990s, salt was applied up to levels of 1,000 pounds per acre. At the 1,000 pound-per-acre level, some weed control was observed. Better weed control would probably require even more salt. As you can imagine, applying salt at amounts over 1,000 pounds per acre has a few side effects.
On a clay soil it could result in the complete loss of soil structure, causing the soil to take on a concrete-like consistency. On sandy soils this effect was not observed, but that is probably because the salt was washed away by rain water that percolates through the soil.
Before you try salt as a weed control, you may also want to consider that few other desirable plants can handle the salt levels of asparagus, so you are going to be stuck with a dead area in your field for decades after it is no longer an asparagus patch.
Tillage is another possible option. It is not a popular method because equipment can cut into asparagus crowns, opening them up to Fusarium root rot and thereby shortening the life of the field. The safest time for tillage is early in the spring before spears begin to grow. However, some people also till immediately after the last harvest is taken. The late tillage will certainly break off some of the spears that could have grown into new fern, using up some of the crowns’ reserve energy.
“Remember to till as shallowly as your tiller will allow,” according to MAAB.
Read more: 5 Tips For Growing And Harvesting Asparagus