With the holiday season over, it’s time to turn our attention to Spring bedding crops. Although here for a brief window, the diversity of these crops means you’re bound to encounter some sort of disease and insect problems.
One way you can head off issues is to plan and prepare now. This post has important tips on sanitation for common spring crop diseases, dipsandearly sprays to prevent key pests, as well as tips on where to spend your biocontrol dollars.
It’s that time of year again where two of our biggest crops cross over: fall pot mums and poinsettia. This means growers have to simultaneously keep an eye on the two biggest pests in the industry: thrips (usually western flower thrips) and Bemisia whitefly.
Here’s how things are shaping up with these pests and where they might be going.
Here in Canada, we’ve been talking for years about research on the highly effective method of dipping your poinsettia cuttings in low-risk pesticides to reduce starting whitefly populations.
Thanks to Dr. Rose Buitenhuis (VRIC), Cary Gates (FCO) and BioWorks, the label for BotaniGard WP has now officially been expanded to include dip applications. This now adds to our arsenal (see below for more dip products).
Read on for the current BotaniGard label and how dipping can help improve your Bemisia whitefly program this year, whether you’re using pesticides or biocontrol.
Entomopathogenic nematodes – used to control fungus gnats, shoreflies and thrips – are often a “gateway bio” into biocontrol use in greenhouses. This is because not only are they effective and easy to use, but they’re generally compatible with insecticide use. Readily applied with regular spray equipment or through drip lines, nematodes can even be tanked mixed with pesticides to save on labour costs.
In this post, I’ll share some of my research at NC State, looking at which commonly used pesticides in Canadian and U.S. greenhouses are safe to use with nematodes.
What’s the first thing you do with your shipments of predatory mites, parasitoids and predators when you receive them? You probably check to see if these natural enemiesare alive before you put them out in the crop.
Now Albert Grimm (Jeffries Greenhouses) and I have come up with a way to check if many of your microbial products are still viable, too.
We’re still in the process of testing these methods for all microbial products, so please consider this preliminary. Right now, we know this works for Beauveria and Metarhizium-based products only (e.g. BotaniGard, BioCeres and Met52). I’m hoping to put the methods up for more products in December.
Figure 1. Various fungi growing on a 3M Yeast and Mold Petrifilm
Distilled (sterile) water. Unopened bottled water will do in a pinch. Do NOT use tap water.
Figure 2. 0.2mL sterile, disposable pipettes that can be obtained from Amazon.ca.
Step 1: Disinfect the water cup and the measuring spoon with rubbing alcohol. Wipe dry with paper towels. Step 2: In one plastic cup, add a small amount of sterile water (a few mL is fine). Keep for Step 4 to act as a control. Step 3. Take a second cup to mix up your product in. Add 200 mL of sterile water. Then add approx. 1/16th of a teaspoon (0.3ml) of product (Beauveria or Metarhizium). To measure, fill the smallest baking measuring spoon (1/8th of a teaspoon) about half way. Stir well. This will give an approximate concentration of 1 g/L, which is similar to recommended rates of these products. Step 4: Take a disposable pipette and fill with sterile water. (Make sure to re-seal your bag of pipettes so they stay clean and sterile). Grab a single Petrifilm and peel back the thin, clear cover on top. Carefully squeeze the pipette to form a line of water across the surface of the Petri film. Step 5. Repeat Step 4 on the same Petrifilm using your product in solution. You can use the same disposable pipette (since it only had sterile water in it previously).
Figure 3. Photo courtesy of Albert Grimm. A 3M Petrifilm used to test the viability of Met52 and BotaniGard. The blank water control indicates that all fungi came from the products, not from the water source (here, distilled water).
Step 6. Gently drop the plastic cover back over the Petrifilm. Write directly on the plastic cover with a sharpie to indicate the position of your “control” water line and your “product” water line (see Fig 3). Store the film between 20-25 °C in a dark location.
Step 7: After a minimum of 16 h (the time it takes for Beauveria spores to germinate), check your Petrifilm. The sterile water line should be blank. The Beauveria and Metarhizium lines should be light blue -the film has a dye in it that reacts to fungi (Fig. 3). Note that this dye reacts to ANY fungi or yeast. Thus, you CANNOT use it to diagnose what fungus is growing. This is why the sterile water control is so important – you want to be sure the reaction is from your microbial product, and not from random fungal spores in your water.
With the growers still tentative in their use of microbial-based products, this viability test may give growers some piece of mind. It will be particularly useful for product that’s been shipped in hot summer months, or in the dead of winter, as some products are sensitive to extreme temperatures. It can also be used to testproduct that has beensitting in storage for long periods.
Note that this is a simple live/dead test. These methods do not quantify how much of the product is still viable. That’s something Dr. Anissa Poleatewich (Vineland) and I are working on, as we think it would be useful to know if your product is decreasing in efficacy over time. So, stay tuned for more information as we perfect our methods.