Should You Spray?

Pest management is an important part of operating any successful hydroponics or aquaponics farm, especially if you're doing it commercially.

After all, an infestation can destroy the hard work and money you've put into growing your own food.

If we experience decreased yield or produce quality in our own greenhouse, it is usually due to some type of infection, which usually can be avoided through a diversified integrated pest management strategy.

Luckily, you have options. There are several methods of spraying in a greenhouse (or even outside) and several organic pesticides can be used to gain control over an infestation.

It is important to note that preventative spraying/fogging is far more effective than trying to control an already infected system.

Here are some tips for spraying in a greenhouse, whether you're a hydroponic or aquaponic grower.

Be safe: Wear Protective Clothing

Pesticides of all kinds can be damaging to humans, so it is important to obtain the proper safety equipment prior to application. We begin by examining the 5 items you will need to get started. You can purchase all the equipment you need at your local hardware store.

  • Respirator: These units have filters which prevent the pesticides from entering your lungs. Consistently failing to use a respirator can result in severe lung damage and other complications.
  • Gloves: Any form of work gloves will work, but cotton gloves tend to absorb more pesticides and ultimately result in skin contact. Organic pesticides are less irritating, but prevention of contact is the best way to prevent any unwanted sickness.
  • Long Sleeves/Pants: This will reduce the amount of skin contact while applying. We recommend using impermeable material like nylon or cheap plastic haz-mat suits.
  • Eye Protection: Although it is not always necessary to use eye protection, it is a good habit to wear all forms of protection.

Four Factors to an Effective Spray

When starting to apply your solution, there are four important factors to remember:

  1. Even application
  2. Distance from the plant
  3. Consistent mixing of the spray solution
  4. Timing your spray

Even Application: Begin spraying with the outermost set of towers working your way up and down each at an even pace. You should be covering all the foliage of plants, but also avoid drenching them(approximately 3 seconds of spray per tower). After finishing the first side of your towers, move in between the next row. Start at the back towers and spray each tower on the left and right of you. Once the towers in the back have been covered, continue moving toward the front of the row.

Distance from the Plant: The sprayer should be positioned approximately 18" away from the plant to provide an even coverage, but avoid drenching the plant. If the solution is dripping off of the leaves after sprayed, it may be transferring more infection than it is preventing. Powdery mildew infections are particularly difficult to remove due to its ease of transfer.

Consistent Mixing of the Solution: Many pesticides including Neem oil, jojoba oil, and pyrethrins will need to be mixed frequently because they tend to separate out of a solution. Simply shake the sprayer vigorously every 5 minutes or so, and the solution will be evenly distributed within the sprayer.

Timing Your Spray: If pesticides or other chemicals are applied in the presence of sunlight, it often results in plant burning, and ultimately plant death. We recommend applying pesticides at twilight, so that the aerosolized pesticide has time evacuate before the sun comes up. Another important aspect is the period of reentry. This is the time period where humans cannot enter the greenhouse after it has been sprayed. Refer to the instructions on your pesticide to determine the period of re-entry.

Sprayers vs. Foggers

To apply these pesticides, we recommend using two methods: using a garden sprayer, and using a fogger. Both are effective at controlling infections and have their own unique drawbacks and benefits.

Garden Sprayers:

Our primary method of application is using a sprayer, which are cheap, and can be purchased at any local hardware store.

They work by pressurizing the bottle with a hand pump, which forces the pesticide through a nozzle. This allows for even coverage.

The nozzle can be adjusted for streaming or sprayed application. Even coverage results in the best control, so we recommend setting the sprayer to the mist setting. This is also the most cost effective method of spraying.

It is important to remember that you will need to clean your sprayer out each and every time you use it to prevent buildup and clogs.

For an extra scrub, try throwing 3/4" granite into the sprayer with some water to scrape of the insides. 

Foggers:
We use foggers for particularly bad infections.

They use an electrical pump to move the solution into a nozzle, where it comes out as a fog. The fog comes out at a fairly high velocity, so it is important to be at least 18" away from the target plants.

Since the solution comes out as a fog, it uses the solution more efficiently and results in faster application than a sprayer.

Foggers are significantly more expensive than sprayers and also require more maintenance, but they last longer and provide even more even coverage.

It is absolutely crucial to clean foggers out every time to preserve their longevity.

If sprayers break, they can be purchased with minimal cash, foggers however, are significantly more expensive.

To clean a fogger, fill the unit up with water, and let the entire solution run through the system by leaving it on. We often prop the fogger hose onto a bucket and let it fog the entire greenhouse as it cleans the solution.

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