Are Foliar Nematodes (Aphelenchoides fragariae) ruining your Hostas?
These pervasive microscopic worms can greatly disfigure a hosta. Here is a short summary.
Foliar nematodes create brown streaks in your hosta leaves. When these symptoms appear depends on your growing zone. (It’s usually August in Minnesota.) Although they may live in your hosta year round, the symptoms appear when these microscopic worms have amassed a large enough quantity in your hostas to begin to damage the leaves. They are prolific egg layers and almost impossible to kill. One of the reasons for the increasing numbers of nematodes the past few years is because a few years ago the toxic chemicals that could kill these annoying worms were outlawed. I have read these same Aphelenchoides fragariae live in about 250 species of plants.
Foliar nematodes can be detected using a magnifying glass. You can have foliar nematodes for a long time but not even know it as their symptoms have not appeared. Thus, it is possible to share, sell or buy infected plants without even knowing it.
What can you do to prevent foliar nematodes?
Purchase our Starter TC or Advanced Starter disease free hostas. These plants are grown in tissue culture plant laboratories and are tested for viruses and nematodes before going into mass production. Most of these plants we sell in our business never even touch the ground.
How can foliar nematodes spread?
They travel via water. If you have hostas infected with foliar nematodes at the top of a slope, you will likely find hostas in the “fall line” below the infected hosta as the nematodes traveled via water to the plants below!
Nematodes can be spread via non-sterilized garden tools that have nematodes on them. It is important to disinfect all garden tools after each cut. In particular, every cut if you suspect nematodes are a problem.
I sadly learned from two government disease experts that nematodes can be spread via animals such as pets, rodents, and even birds. That is another reason why it is close to impossible to guarantee that anything grown in the ground does not have foliar nematodes. One garden affected can spread foliar nematodes long distances in more ways than we think, so you need to be wary of where you get your plants.
As mentioned, the same foliar nematodes in hostas are appearing on 250 different species of plants now. Some government plant disease officials told me they felt the many sources of supply of non-regulated plants sold on the internet are causing plant diseases to spread more rapidly. Again, many people do not even know the nematodes are in their plants.