From time to time there is a renewed concern about virus and foliar nematodes in hostas. In light of this, I thought I would again share with you the policy and procedures we have here at Green Hill Farm to combat these pests.
Foliar Nematodes
In 1990 and 1991 I was one of the first to identify foliar nematodes as a pest problem in hostas. I have developed a very simple philosophy in dealing with them. We know chemical treatments do not totally eliminate foliar nematodes from hostas and heat treatments while effective are not practical for a large number of plants in the nursery or in the garden. As a result, eliminating all infected plants and any suspicious surrounding plants is the easiest and cheapest way to deal with the problem.
Here is our program for combating foliar nematodes. We buy only hostas from tissue culture labs. We buy no bare root plants. Foliar nematodes can be eliminated through the tissue culture process, so we start with nematode-free plants. Our job is to keep them that way until they arrive in your hands.
We do this two ways. First, the nursery has been constructed to be a hostile environment for foliar nematodes. We grow all our hostas in containers, none in the ground. All the growing areas of the nursery are covered by 2-3 inches of gravel, no ground cloth where the worms may hide and survive. We keep these areas “clean”, free from leaves and soil. We remove all hosta foliage from these houses in the winter. Our hostas are grown in just a little too much sun so that the plants and the black pots get hot and dry out.
Secondly, all our hostas move through the nursery in only one direction, we do not move plants back and forth. They are potted in hoop houses that have never had foliar nematodes and shipped directly from there. They are not mixed with ferns and other perennials that might bring in a problem. We also turn over our inventory very quickly, in one to two years. We rarely divide hostas anymore and those that are divided never return to the liner houses.
We inspect the nursery every week during the summer and immediately throw away any plants that may show symptoms of foliar nematodes. We also throw away all the other plants within 4-6 feet of the infected plants. We use not chemical treatments since they may reduce the nematode population and mask symptoms that will return in your garden. I can report that we have not had any infected plants in our sales houses for the past two years and only a handful in the previous five.
All this is very expensive. The tissue culture hostas we buy are frequently two or three times the cost of bare root hostas. We must grow them longer, usually at least a season for wholesale stock and two seasons for retail plants. The longer a pot sits in the nursery the more it costs us to produce. We also do not divide them reducing their cost. Plus gravel is not cheap. We feel the higher prices that we need to charge reflect higher quality, a clean hosta is a better hosta.
Virus
I have seen viral infections in hostas since the mid 80’s around the hosta world. Virus on hostas is nothing new. Fortunately, I have had very little experience with it our nursery, I have seen very few plants. Part of this is because we buy tissue cultured hostas. Virus may pass through the tissue culture process but I have not had a problem with the labs I deal with.
Our policy is again simple. Since there is not cure for a hostas infected with virus, we just throw away any plant that shows any symptoms immediately. Fortunately, viruses do not spread easily from hosta to hosta so there is no need to throw the surrounding plants away, although the area is then inspected regularly.
Our Guarantee
We have a satisfaction guarantee for all the hostas that we sell. If you are unhappy with any hosta you receive from us for any reason we will be glad to replace it or refund the cost of that plant. In regard to foliar nematodes and virus, here is a good rule of thumb to use. If you purchase a hosta from Green Hill Farm this year and symptoms of either foliar nematodes or virus appear later on this same year, please let us know. We will refund your purchase price no questions asked and we will investigate if our plants show symptoms. Just a reminder, if you put a clean hosta next to a badly infected hosta in the spring, by fall it too may show symptoms of infection.
We want you to love the hostas you get from Green Hill Farm. Please tell us if you ever have any problem with our plants. With your help we can continue to improve our nursery operation.