Commonly known as root rot, Pythium is a water mould that feeds on the root system of plants impacting growth that could eventually result in the plant’s death. This pathogen can emerge into the greenhouse environment through several channels – from plant plugs to soil that enters greenhouse walkways. The preventative techniques include sanitation, changing growing mats frequently, keeping soil well drained and not overwatering. Pythium are water moulds, Hausbeck emphasised, so it’s important that overwatering is avoided. 

She said that for many growers, this problem is simply accepted as part of greenhouse life.  “Root rot can certainly cause death, but it can also create less optimal growth. It is one that can be frustrating for growers and can lead to fungicide applications that didn’t hit the mark. When we take a look at some of the products that we have, we just don’t have a lot of new materials for Pythium. It would be nice if we can increase that for the growers.” 

Despite the longevity of the pathogen, the tools to manage and combat Pythium have had very little development. However, Hausbeck’s research at Michigan State University is hoping to change this.  

From fall 2011 to spring 2013, Hausbeck and her research team extracted spring and fall samples from greenhouses in the three main Michigan areas, including Grand Rapids, Kalamazoo and Detroit. She wanted to determine if certain species of Pythium were regionally specific or crop specific. By narrowing down the location of specific pathogens, researchers can then develop pathogen-specific treatments. The samples included a range of crops that were prone to the Pythium pathogen, including geraniums, snapdragons, poinsettias and lilies.   

Hausbeck’s initial findings unveiled that certain Pythiums tended to fare better under specific weather conditions. Pythium ultimum was found in almost half of all of the samples, but most frequently on poinsettias. She commented that it interesting that this same species seemed to be nonexistent in greenhouses in warmer climates. This leads to the question on whether this species could be weather specific. 

Her research findings uncovered that the 25% of the samples were host to Pythium aphanidermatum, which was found most frequently on geraniums and snapdragons, while the remaining 25% were host to the species Pythium irregulare.  The research team discovered that each of the Pythium species tended to respond a little differently to temperatures in addition to having a crop preference. 

These initial findings lead to the speculation whether it would be better to treat Pythium based on specific crops or weather. “We are trying to see if we can better tailor some of the fungicides towards different crops and the types of Pythium that are being seen more frequently on the certain crops,” said Hausbeck. “It is one of these areas that there is a lot to learn; it is not necessarily a hot button. But it is one of those headaches that growers often have to cope with their crops.” 

Hausbeck and her team are currently working in an on-site greenhouse lab in which they will research whether it’s better to tailor some fungicides towards the specific Pythium that is found most frequently on a crop. The new research is going to be looking at the disease accessibility to the four culture plants prone to Pythium with a focus on the three strains that were seen across the Michigan greenhouses. 

Hausbeck wonders whether there are differences in cultivars of plants that tend to be a bit more pathogen-resistant to Pythium. The new research will also look at how each of the Pythium isolates work on the individual crops—in particular, looking for any differences on how the Pythium reacts on plant crops and in weather.

Source: Stocksorb