Home » Plant Pest Control: The Three Dangers.

Plant Pest Control: The Three Dangers.

Managing and controlling an indoor grow environment is hard enough; with variables such as getting the right setup, following a nutrient schedule and keeping the right temperatures, the last thing your grow needs is plant pests and diseases potentially ruining all of your hard work and effort! In this post, we take a look at the three main potential dangers that can plague your plants. We’ll teach you plant pest control and how to take preventative measures and how to take action if you notice a problem!

Danger 1 – Spider mites (Tetranychus urticae)

plant pest control spidermite
Fully-grown indoor spider mites & their eggs.

For growers, the main enemy is the dreaded red spider mite. Also called the ‘two spotted’ mite, because they don’t develop their red colour until they mature. Contrary to popular belief, spider mites are in fact, not insects. They belong to the arachnid family, the same group as spiders & scorpions. As spider Mites aren’t insects, spraying insecticides will not kill them! Instead, some commercial growers use ‘miticides’ such as abamectin. These are potent nerve agents that act on the same type of nerves found in the human brain & spine, causing potential harm. So how do you control spider mites safely? We suggest the following, based on the Integrated Pest Management (IPM) approach.

1. Regular monitoring.

An adult female mite is no more than 0.5mm long, so you will need a good hand lens to spot them, we recommend one with a light because spider mites prefer to feed on the underside of leaves where it can be harder to view them. Check your crop at least once every few days. If you wait until the spider mites have spun a web before you take action, you already have an infestation, and control will be a lot harder.

2. Environmental control.

Spider mites thrive in dry air. Make sure your humidity is high enough for good plant growth & health. Misting also helps as this both increases the humidity & when the droplets land on a web, It makes them far easier to spot. Spider mites also thrive in warm conditions, so try to keep the grow room cooler if you are constantly getting infestations, Spider mites grow fastest at 27°C. Spider mites will eat many different types of plants, they will easily infest bananas, cucumbers & peppers. So if these are not your main crop, avoid having the odd plant in your grow room.

3. Chemical control.

Spray2Grow’s spider mite protection spray makes your crop unpalatable to mites, that physically attacks their exoskeleton. If you have webs on your crops, try to remove them before spraying. Removing webs disrupts the mites, and allows the spray to reach the foliage without bouncing off. After a couple of days spray your crops again, Each one of those female mites will have laid up to several hundred eggs, waiting to hatch & start an infestation all over again!

A spider mite destroys approximately 22 cells in the leaf every minute as it feeds. The necrotic patches left behind will permanently damage the leaf. So once you have treated the plant do not expect the leaf tissue to recover, this is why it is good to be pre-emptive and take action beforehand!

Danger 2 – Mildew (Leaf Fungi/ Disease).

Tomato plant with powdery mildew. (Notice the fluffy texture).

Mildew is not one type of organism, It is just a word we use for diseases where the symptoms of infection is ‘fluffy growth on surfaces, whether that is on plants or the walls of your house. For the majority of growers, ‘powdery mildew’ caused by fungi will be the main problem they encounter. So how does powdery mildew spread to your grow? It cam be caused by rain/ irrigation splashing spores onto plants, spores floating in the air or coming in on an infected plant or growing media. It thrives in humid air, warm air & dry soils. Whilst they all look very similar, the specific species of fungus causing it will differ. Although nearly every type of plant can suffer from mildew, most mildew strains will only affect one type of plant or close relative.

The Spores from mildew are a concern to humans, as they can cause irritation to the lungs. Sometimes this is mild and temporary but it can be seriously debilitating and is what doctors call ‘farmers lung’. So be careful when moving infected plants in unventilated areas, especially if you are old, suffer from allergies or weak immune systems.

How do growers protect their crops from mildew?

The are a few synthetic fungicides that can be used to control mildew, however there has been a lot of them withdrawn because of questionable safety to human. There has also been reports of natural extracts being effective at controlling mildew, such as garlic, ginger & acontium to name a few. Unfortunately there are problems with these natural remedies: The majority are untested and may be unsafe for humans, some are unregistered and illegal to use some could be complete myths!.

This is where Spray2grow’s Mildew protection spray comes into play. Spray2grow contains active ingredients that are authorised for use as a bio-stimulant and bio-fungicides in the UK and the EU under organic farming regulations. Its proven to be effective on high value hydroponic crops and unlike conventional fungicides, Spray2grow does not poison the fungus in order to kill it! Instead Spray2grow uses the fungi’s weapons against itself. When mildew fungus attacks a susceptible plant it releases chemicals to stop the plant detecting that it is there, normally this allows the fungus to feed like a parasite. Unfortunately for the fungus, Spray2grow releases massive amounts of the signalling compounds extracted from related species, this suddenly makes the plant detect the presence of a pathogen and turns on its chemical defences!

Danger 3 – Thrip Infestation.

plant pest control Thrips
Thrips through various stages of its life.

6000 species of thrips have so far been discovered, but there could be many more as they are very small and don’t fly around much (so don’t get caught as often in traps). The main enemy of growers are normally those that eat many types of plants (termed polyphagous) including western flower thrips & tobacco thrips. You will be able to identify thrips on your crop by their yellow or brown colour, with six legs, slender body & its wings held back over its body. Thrips lifecycle usually goes as follows, eggs are laid inside the plant (so you usually don’t see them) When the eggs hatch the turn into tiny transparent larvae, that starts eating your plants. The transparent larvae moults to form a larger but still wingless second larvae. They eventually form into a winged adult, that will continue eating plants and will lay eggs, regardless of whether it has had sex or not.

The larvae are around 0.5mm long & transparent, so you will need a hand lens to be able to spot them. Adult thrips can grow to around 2mm long, but by that time your plant will be fully infested. Unlike most pests, thrips feed on the upper surface of the leaf, so look for silvery-white damage and any crawling larvae.

How can growers protect their plants from Thrips?

You can try to be pre-emptive with sticky traps that catch the egg-laying adults before they are able to create an infestation. Blue sticky traps will work the best for this but yellow traps work as well. But we believe the most effective way to stop a thrip infestation would be through Spray2grow’s thrips protection spray. It combines natural ingredients that make the plant unpalatable to thrips, with other compounds that physically destroy the insects exoskeleton. When spraying your plant with the protection spray, spray until droplets begin to drip from the tips of the leaf. Spray the surface of the growing media as well to kill those pesky pupae.

Re-apply the spray 2 – 4 days later to kill any larvae that have hatched from eggs buried inside the lead tissue. Please note: you should wear full PPE, especially if you are allergic to lemon grass oil (Just one of our active ingredients).

Spray2Grow Protection Sprays for plant pest control, readily available to retail in 500ml bottles from TGW distributions.

Please visit Spray2Grow Instagram to learn more about plant pest control and more in depth scientific information on plant pest control.

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