Greenhouse Game-Changer: Innovative Approach to Water Mold Control

It’s important to understand some of the fundamentals of water molds to be able to properly prevent growth. Relatives of algae, water molds are unique organisms that also thrive in aquatic environments. They often grow in sediments rich in organic matter but low in oxygen. Water molds are exceptional pathogens because they have developed a fungus-like lifestyle, capable of thriving in soils that are rich in organic material and very wet. The combination of these unique characteristics makes them particularly troublesome to greenhouse managers, as they’re able to grow and reproduce in irrigation ponds and thrive when transferred through irrigation systems, ultimately making their way into plant production. Once introduced, they can colonize the soil profile, attacking the plant roots and stealing vital nutrients for growth. This is why effective water mold control begins with irrigation ponds and surface water, not just isolated within the greenhouse.

Some common types of water molds are Globisporangium and Phytopythium. These are newer names based on their molecular features, however, these pathogens and the diseases they cause are generally known as Pythium. Additionally, Phytophthora, which includes over 100 species, is another notorious type of water old that is often even more pathogenic than Pythium. The severity of the diseases these water molds cause depends on various factors, including environmental conditions, the host plant, and the specific species of the pathogen.

An Ounce of Prevention is Worth a Pound of Cure

Most commercial greenhouse and nursery operations have a successful disease management program that often includes cultural, biological, and chemical control options. Fortunately, there are chemical options that specifically target water molds including mefenoxam (FRAC 4), fenamidone (FRAC 11), etridiazole (FRAC 14), cyazofamid (FRAC 21), dimethomorph and mandipropamid (FRAC 40), fluopicolide (FRAC 43), amectocradin (FRAC 45), oxathiapiprolin (FRAC 49 and the phosphonates (FRAC P07). However, with aggressive plant pathogens like Pythium and Phytophthora, the best and most cost-effective strategy is prevention. These diseases can turn on and off like a light switch, making curative or reactive applications ineffective.

Acting early, especially during the initial growth stages, is more effective and offers better returns. This is because larger, more mature plants have stronger root systems that can better fend off new water mold invasions. A good proactive method involves applying standard chemical treatments before planting and during the early growth stages. This helps prevent the spread of water molds that might come in through irrigation water.

There’s also a recently approved, innovative solution for managing water molds directly in ponds and surface waters. Cutrine® Plus is now available for use to control water molds in aquatic environments, like irrigation ponds. It’s a copper-based pesticide that targets specific enzymes found in algae. Since water molds are genetically related to algae and share these enzymes, Cutrine Plus effectively controls them in these aquatic environments.

A Preventative Strategy with Cutrine Plus

Cutrine Plus is a fast-acting solution against water molds, achieving partial control in just four hours and full control within 48 hours of application. Its chelated copper formula ensures the active ingredient lasts longer, keeping copper dissolved in the water for 7-10 days, even in still water. This reduces the chance of water molds rapidly re-establishing. Safe for fish and other aquatic life when used according to label rates, Cutrine Plus should be applied at a rate of 0.6 to 3 gallons per acre-foot of water, based on the perceived abundance within the waterbody. Additionally, it is a cost-effective option for controlling water molds.

Water mold populations generally begin to increase in the early spring when temperatures rise and dormant populations begin to grow. The most proactive control of water molds involves the integration of Cutrine Plus into a routine management program starting with a low dose (0.6 – 1 gallon per acre foot) in the early spring, to target and prevent early expansion. It’s important to apply low dose applications every 2-4 weeks to keep the molds from growing back and to block new molds from entering with surface water, especially during rainy periods. This proactive approach is not only cost-effective but also ensures that seedlings develop strong root systems, offering extra protection against water molds that might get into the irrigation system later in the growing season.

Although prevention is the primary strategy when combating water molds, Cutrine Plus can also be safely used at higher doses (1.2 – 3 gallons per acre foot) for reactive control of irrigation pond water mold populations. We know that water molds flourish in waters rich in organic matter, often where algae are abundant. By applying Cutrine Plus to ponds affected by algae, the spread of water molds into irrigation systems and greenhouses can be significantly reduced, giving growers another management tool and additional peace of mind.

Treating the Source of Water Mold Growth

Identification of water mold symptoms within the greenhouse is a key indicator of the presence of water molds in irrigation ponds, as the parasites are likely being introduced through the irrigation water source. In these instances, using both standard chemical treatments for immediate control and Cutrine Plus for targeting the source in the pond is a highly effective strategy to eliminate the problem. Therefore, Cutrine Plus can be considered both as a standalone proactive measurement to prevent the introduction of water molds into the greenhouse and a complement to conventional control to reduce the symptoms after water molds have already been introduced in the greenhouse.

The battle against water molds, particularly in greenhouse and nursery environments, calls for a blend of traditional and innovative approaches. While traditional chemical treatments play a crucial role, the introduction of Cutrine Plus has marked a significant advancement in controlling these molds, especially for proactive control in aquatic environments. This comprehensive management strategy, combining early prevention and effective treatment, is essential for maintaining healthy plant growth and ensuring the success of greenhouse and nursery operations. Growers can more effectively safeguard their crops against the detrimental effects of water mold infestations.

Dr. Byran Fuhrmann is currently the Aquatic Technology Development Scientist at SePRO Corporation. He focuses on developing products to improve water quality and is the lead inventor of 7 patents.

Dr. Aaron Palmateer is Director of Agronomy at Harrell’s, LLC where he began working in August 2022. His expertise lies heavily in plant diagnostics and managing plant pests, diseases and disorders.