Poinsettia pointers

The trial is a collaboration between KSU, Ecke, and the Dummen Group. The young plant producers send 15-30 of their newest cultivars for the students to grow and test.

 

The students get a chance to compare side-by-side the subtle but significant differences the various genetics bring to the cultivars, and the collaborating companies receive data on how the crops perform in a Midwest environment. It’s a win-win.

 

“Plus, we end the whole shebang with a consumer preferences survey and open house that the students put on,” Williams says. “We invite local consumers and regional industry to swing by and look at these new cultivars that have not been released yet and might be released, as well as some tried and true ones. Folks from our local industry will come and see a cool cultivar and want to add that to their production mix in subsequent years.”

 

Williams has learned a lot over the years about successfully growing poinsettias, and she has developed a system that works.

 

Poinsettias are extremely susceptible to root rot disease. Williams says different root rot pathogens cause trouble depending on where you currently are in the production cycle. Poinsettias with Pythium root rot are often stunted, wilted despite media wetness, and slightly chlorotic. The roots are often brown, squishy and exhibit “rat tails,” where the outer cortex of the root slips away from the vascular tissue. Pythium is more often talked about, but later in the crop production cycle, for example, Phlebiopsis root rots can be very problematic.

 

To combat root rot, Williams works with her students on establishing a healthy root system up front, at the beginning of the production cycle and making sure the plants have healthy microbial populations.

 

“Biofungicides like Trichoderma, which are beneficial fungi, can really inoculate the root system,” she says. “That will help prevent any pathogenic organisms from being able to get a foothold if they do occur later on in production. At the same time, if we have a student grower doing a lot of overwatering, (root rot) most likely will set in due to the watering practices. So we work with them on getting that piece of it correct as well.”

 

At KSU, Williams uses a combination of biological and traditional pest management practices. She starts with a biofungicide drench right after potting to establish healthy microbial populations in the root system, establishing a healthy root system.

 

Whiteflies can also be a problem early in the poinsettia production cycle. To avoid letting whitefly populations take hold early in the production cycle, Williams uses parasitic wasps and other biologicals to keep pest populations low during that first month to six weeks of the production cycle before coming in with a systemic insecticide that can take care of any potential pests that would feed on the plants.

 

In recent years, she has had more frequent thrips outbreaks on poinsettia crops. She uses predatory mites to attack the thrips.

 

“From an IPM standpoint, what’s really worked well for us is biological controls over the first half of the crop until we can get to that systemic conventional insecticide application and finish out the crop that way,” Williams says. “That means you have to keep pest problems abated with biologicals so they don’t start spinning out of control. If they get out of hand, we would need to hit the crops hard with conventional pesticides later.”

 

Williams says the biologicals seem to work better when used early in the production cycle. When the plants are smaller, there is less foliage for the beneficial insects to hunt through, leading to more effective coverage.

 

Pest management up front is important to help the crop succeed. It helps minimize root rot problems and make sure any initial pest problems are unable to gain a foothold.