About Plant Pest & Disease Control
It's one of the most disheartening things to walk into your indoor garden and to discover an infestation of pests or a fungus infection causing damage to your carefully grown plants. Where this is concerned, an ounce of prevention is worth a pound of cure. Unfortunately many growers (particularly new ones) do not start using preventative measures until it is too late and damage has already been done. We'd strongly recommend that you don't learn the hard way - use preventative measures in your garden.
Plant Pest Prevention
Thrips, spider mites, whitefly, greenfly, blackfly, leaf miners, aphids - they're all garden pests that can ruin a crop. There are several ways to help prevent pests getting into your garden. The first is by physical means with the use of air intake bug filters. These go over the end of the fresh air intake and help to trap pests being sucked in from outside. Pests can also be brought in by them hitchhiking a ride on anyone visiting the garden, be it yourself or a dog or a cat. This can help to be prevented by changing your clothes before entering your indoor garden if you have been outdoors.
The other method is by the use of deterrents. Certain plants have evolved to produce completely natural compounds, certain essential oils. The mere presence of these has pests scurrying to escape. These compounds can be found in products such as our favourite: Ed Rosenthals Zero Tolerance Herbal Pesticide. This is almost a miracle product and once diluted it can be either sprayed or, preferably used in a fogger like the ONA Misting Dome. The essential oils are as effective as Neem oil but does leave any residues. The essential oils are released into the grow space creating a hostile environment for pests. Use it on a regular schedule (a couple of times a week should be ample). Pests will simply not want to be there. It is also completely natural and completely safe to use around crops for human consumption. However, it is EXTREMELY STRONG. We know very few growers that use it at full strength (50ml/litre of water). We would recommend using it a third to half that (17-25ml/litre of water). Always do a leaf patch-test at the intended strength and wait 24 hours. If any leaf-burning appears, reduce the strength and test again. Some good general purpose alternatives are as follows:
- Evoponic Force Field - Strengthens plants' immune systems
- BioBizz Leaf Coat - Coats and protects your plants in a breathable skin that insects cannot penetrate
- Cannacure - Like BioBizz Leaf Coat - Protects your plants with a breathable skin
Plant Pest Eradication
If you are unfortunate to get an infestation, there are plenty of products to help. Please Note: Spider mite eggs are resistant to most general purpose pest treatments. If you have an infestation of them you will usually need treat your plants at least 3 times over the course of about 10 days. This is to kill them as they hatch before they can lay any eggs themselves, and continue doing so until they are all hatched and dead.
If your crops are intended for consumption then you should be careful to choose one that is safe. Some use chemical pesticides and are intended to be used only on ornamentals such as roses. The ones that utilise natural ingredients are generally perfectly safe:
- Ed Rosenthal's Zero Tolerance Herbal Pesticide - This is not just a preventative, it can get rid of infestations too. Please Note: Spider mite eggs are resistant to it so if you have an infestation of them you will need to use it as a foliar spray or in a fogger at least 3 times over the course of about 10 days. This is to kill them as they hatch.
- C-No Insects 4C-Field - Treats pests in a unique way. It contains safe, statically charged ingredients that kills pests as well as some moulds, bacteria and viruses. It may leave a slight, but safe, residue.
- Plant Magic Bugicide - Even treats Powdery Mildew
- Pyrethrum 5EC - Based on a substance found in Chrysanthemums but it is harmful to cats and aquatic life long term.
The following products are based chemical pesticides and are very powerful but should only be used on ornamental crops and nothing edible:
- Guard 'N' Aid PestOFF Plus Concentrate - Artificial manufactured chemical based on Pyrethrum so will be harmful to cats and aquatic life
- Guard 'N' Aid PestOFF Midi Fumer - This is a fumer based on the Plus Concentrate above. Similarly harmful to cats and aquatic life
- Cypermite - contains a potent chemical pesticide called Cypermethrin which is toxic to bees, spiders and aquatic life. It does break down when on plants but can remain active on surfaces, like fabric and walls, for weeks.
Plant Molds like Powdery Mildew and Botrytis
Just like a pest infestation, it can be heart-breaking to walk into your grow room and see mold on your flowers, fruits or leaves. Powdery mildew tends to affect leaves and is slightly slower to cause crop loss, but when it spreads across a crop it reduces photosynthesis and therefore plant growth and yields. Once botrytis or other types of mold have taken hold they have a horrible tendency to spread like wildfire and be difficult to halt and get rid of. As with pests, prevention is overwhelmingly better than cure. The best advice is don't let it get a hold. Fungal spores are everywhere - in the air and on surfaces. All they need to get started is the right conditions which is usually a combination of high humidity and a plant that has been weakened by any number of causes - drought, over/under feeding, heat etc.
Keeping your grow space non-conducive to molds is the starting point. Fungal spores will germinate when temperatures are mild (20-25°C), there is moisture around, and there are some nutrients around (as on the surfaces of plants). The ideal germination temperature is also the ideal temperature for growing plants so there is not much we can do about that. Nor can we do much about the fact that plant surfaces are "nutrients" for mold spores. So, that leaves moisture levels. Humidity levels are key here. If they become high enough then fungal spores will germinate and get going. If you can keep relative humidity (RH) levels moderate (roughly 60% in veg and 50% in fruiting/flowering) then this will keep mold risk low. Much higher than this brings increasing mold risk. An extraction system will draw humid air out of the grow space and draw in fresh air. This also has the benefit of maintaining CO2 levels in the garden space. Every grow space should have one. If all else fails, a dehumidifier may help. Stagnant air close to plants becomes damp. Make sure that you have good air circulation around them with a decent circulation fan or air diffuser.
Secondly, keeping your plants healthy is very important. Mold spores love a plant that has been weakened in any way. Stressed plants have weakened immune systems and often have damaged surfaces - sometimes not visible. For example, plants that have been heat damaged, or have wilted because of a lack of water may have splits between the cell walls. This gives mold spores a place to get in and germinate. Be very careful not to over or under feed your plants and don't let them wilt.
Another way of reducing mold risk is with an ozone generator. Ozone has a deadly effect on mold spores as well as bacteria, viruses and odours. However, it can be harmful to humans too in high enough concentrations. Make sure you get one with the correct output levels for the size of your grow space and turn it off for a while before tending your garden.
Using an extraction system, a circulation fan, a dehumidifier and an ozone generator can alll help slow down the spread of mold. However, there are products that can be used to treat the problem.
For Powdery Mildew:
For Flower Rot:
Root Diseases like Pythium
Root diseases are no joke and unless you grow in DWC or Aeroponics you may not know it has taken hold until it is too late. Root fungal infections like Pythium turn healthy white roots into a slimy sludge and once that has happened the plant is pretty much doomed. Other types of root rot include: Brown root disease (Phellinus noxius), White root disease (Rigidporus lignosis), Black root disease (Rosellinia pepo pat). Once root disease has taken hold, the plant becomes cut off from its source of water and nutrients. The plant wilts and yellows. The plant becomes stunted and will eventually die.
Preventing Root Diseases
As always, prevention is better than cure. Root diseases can occur at any time but healthy, undamaged roots in a good "environment can often fend them off. Root diseases thrive in a low oxygen and constantly wet environment. If you grow in a medium like soil or coco then be careful not to overwater. Always clean (and even sterilise) your pots between each grow. Never keep the medium constantly wet. Always allow the medium to dry a little in-between waterings. As the plant draws up the water out of the medium, Air (containing oxygen) is drawn down into it. When you water always get about 10-20% run off out of the bottom of the pot. This helps to flush out waste products. Always use an appropriate size pot for the size of plant. A small plant in a large pot means that the medium stays wet for too long. When using soil, added perlite (or clay pebbles) help to let it drain well, prevent clodding & compacting, and help keep the medium oxygenated. Even if you follow these tips, we recommend you use one of the types of additive to ensure root diseases don't take hold
There are 2 main types additive to prevent root disease. The first type keeps the root zone sterile. They are almost all based on peroxide (H2O2).
The second type "inocculates" with beneficial microbes. Beneficial microbes are amazing things. "Biological gardening" has a whole host of benefits. It is based on 2 types of beneficial fungi: Mycorrhizal and Trichoderma, as well as a cocktail of beneficial bacteria which do a whole host of jobs in the root zone. Mycorrhizal fungi are symbiotic with plant roots. They attach themselves to plant roots and produce filaments which spread through the grow medium. The fungi then feed water and nutrients to the plant roots. In return, the plant sends carbohydrate produced by photosynthesis down to feed the mycorrhizal fungi. This symbiotic relationship has evolved and developed over millions and millions of years in the natural world. Trichoderma fungi are highly aggressive to other forms of fungus that try to invade its space, yet leave mycorrhizal fungi alone! Trichoderma actively attack and digest fungi that cause root rot. Beneficial bacteria do various beneficial jobs from enriching the soil with humus to fixing nitrogen. It is well known that the first microbes to occupy the root zone will generally be dominant on a permanent basis. They make it incredibly difficult for other strains to muscle in and take hold. They also encourage root growth and generally improving the medium and rhizosphere.
Please note: Peroxide sterilisation products will kill the beneficial microbes. The 2 types of additives should not be used together. The 2 methodologies of growing are completely incompatible.
Additives to keep the root zone sterile:
- Silver Bullet Roots - Definitely the best steriliser. It is the only one with added silver. Peroxide tends to break down quite quickly (within days) and then it is ineffective. Silver stabilises it and makes it more effective. It works for weeks and weeks!
- Pythoff - Peroxide based steriliser
- Liquid Oxygen - Peroxide based steriliser
Our Favourite Additives for Biological Gardening:
- House & Garden Roots Excelurator Gold for non-hydroponics (Hand-watering in Soil/Coco) - Contains beneficial microbes and coats roots in a protective film. It has been shown to cure root diseases. Superb
- House & Garden Roots Excelurator Silver for hydroponics (DWC, Dripper, Flood & Drain etc.) - Exactly the same as the one for hand-watering but it is a low-foaming formulation. Superb
- Ecothrive Biosys - A potent formulation containing the best beneficial fungi and bacteria. Superb
- Ecothrive Neutralise - This is a water conditioner that neutralises the chlorine & chloramine in tap water which inhibits/kills beneficial microbes. Every organic gardener should use it! Superb
- Advanced Nutrients Carboload - An inexpensive carbohydrate feed for beneficial bacteria. It feeds them sugars so your plants don't have to!
Use a combination of the above, along with a good organic feed & soil, and a sensible watering schedule and you shouldn't experience any problems with root rot. If you use a quality organic feed, like Plant Magic Oldtimer which contains molasses, you won't need to use a carbohydrate additive like carboload.