Growers test new species to evade pests and reduce pesticide
Pennsylvania is one of the largest Christmas tree growers in the United States. Like most farmers, they often use pesticides and herbicides to make their trees sturdier and more attractive to holiday decorators. But growers are looking for ways to evade pests and diseases and reduce chemicals on their farms without sacrificing the perfect tree.
At Schmidt’s Christmas tree farm in Chester County, Ellis Schmidt leads me up to a patch of trees about knee high.
Schmidt: We had about 700 trees left when we got the field filled last year. So I lined them out in what had been our vegetable garden.
These are Fraser firs, one of the two most common types of Christmas tree grown in Pennsylvania.
Schmidt: I would think over half of them are dead. And probably a large number of the ones that are off-colored now will be dead by spring. So this is a good example of what phytophthora does to you.
Phytophthora is a root rot disease that lives in the soil. Schmidt knows he can’t grow Frasers in this spot; but the next row over – just a foot away – is a healthy line of trees.
Schmidt: The bottom row is Douglas fir and they look fine.
Douglas fir is the other popular Christmas tree in Pennsylvania. Together with Fraser it makes up nearly 75% of the industry, says Penn State professor Rick Bates.
Bates: So when you get into a situation like that, if you do have pest problems, well, now you’re in a situation where most of your acreage could potentially be affected.
A devastating example is chestnut blight – a fungal disease that essentially obliterated chestnut trees in North America. Bates and Schmidt have paired up on a project to diversify Christmas tree stock.
Bates: I’m giving them different sources or different varieties of Nordman fir or Turkish fir as well as some of the other Mediterranean firs, to plant them out on their farms under their conditions.
Several tree farms are part of the experiment. Schmidt’s is in the warmest climate and will determine how the trees tolerate hot weather.
Bates: What we’re hoping is that it would decrease the pest prevalence and subsequently the pesticide use.
That’s because many diseases are species-specific, meaning they only affect particular types of trees. Schmidt sprays his Douglas firs with a pesticide to prevent a disease called needle cast.
Schmidt: All growers would like to reduce the spraying. It’s also very expensive, the spray material has gotten a lot more expensive in just the last couple of years.
The environmental and health concerns of growers and customers also has the industry seeking chemical-free farms. So far the experimental trees are two years old. One of the test species, the Nordman, is a popular choice in Europe. It’s branches are waxy and full, and it looks healthy, just like the other five test species.
Schmidt: We have not lost any, which was interesting, because they’ve had no special care, as you can see. We treat them just like any other plant that we put in the first couple years.
Schmidt says he doesn’t know whether any of the trees will turn out to be a commercial option. Keeping them alive is only one factor.
Schmidt: Second it has to have the characteristics the customer wants. and certainly needle retention is high on that list. So even if we get a tree that we can grow very well if it doesn’t hold its needles well in the house we really don’t have anything that’s commercially viable.
Bates at Penn State expects that in 10 or 15 years the next best Christmas tree species could replace Fraser or Douglas firs – but he’s unclear which species it will be.