The idiom goes ‘prevention is better than cure’ and is touted by professionals across the board from dentists to mechanics, and gardening is no different. As with all things health related, prevention far outweighs cure, as by the time a cure is needed, damage has already happened. So when it comes to gardening, how can you prevent pests and diseases from causing damage to your plants?
There are several different factors which can cause plant pests and diseases, or at the very least, give them ideal conditions in which to thrive.
Basic environmental practises apply to any form of gardening, whether outdoors, indoors, hydroponics, windowsills etc…
Water – it’s the most basic things about growing plants, but I don’t just mean watering, but humidity as well. As a general rule seedling need higher humidity to stop moisture loss before roots develop, and mature plants require lower humidity to allow for transpiration. Too much humidity leads to mould and damping off, and too little humidity can lead to leaf damage and proliferation of spider mites. Remember ideal soil composition is 50% solids (minerals, rocks + organic matter), 25% AIR and 25% WATER! Too much water leads to root rot and too little to dehydration, both of which weaken the plant and allow it to be attacked by P&D. Also high temperatures combined with water reservoirs/tanks can lead to Pythium. Control measures vary depending on your growing method, but a simple temperature/humidity monitor can help (especially if it records the max/min).
Ventilation – the movement of air is important when it comes to indoor/protected plants. The air movement can help to balance the humidity and stop pockets of damp building up. Care should also be taken with outdoor plants that are bushy with dense foliage as restricted air flow can lead to mould and other disease such as fungal scab in apples. Regular pruning to allow air movement is recommended.
Large ventilation fans at Longwood Greenhouses, PA
Light – restriction of light can lead to proliferation of mould and fungus as well as reducing photosynthesis in affected leaves, leading to necrosis (death of the leaf on a cellular level). Regular pruning can help, also be aware of the number of light hours that the plant needs at various growth stages and is the amount its getting.
The basic rules of hygiene that apply to humans also apply to plants. It’s easy to think with them growing in dirt that using dirty secateurs/snips is ok, or that dead leaves are ‘part of nature’, but clean hygienic practises will reduce the likelihood of pests and diseases. Recently leaf-miner moths have been causing problems for horse chestnuts and they are known to live and over-winter in the leaf litter at the bottom of horse chestnut trees.
Any time you are going to cut a plant, whether this is removing leaves, harvesting fruit or pruning, a clean sharp implement should be used. The cleanliness reduces the chance of infection in the ‘wound’ by bacteria or fungi and using a sharp blade reduces any chances of tearing the ‘wound’ which would reduce healing time and give a larger surface area for infection.
The removal of dead leaves (both on and off the plant) as well as any diseased or damaged parts of the plant should be standard practise (known as the three D’s). However be careful not to break out the chainsaw every time a leaf becomes slightly yellow, simply wait till over 50% of the leaf appears irreversibly damaged/dead before removing. With diseases however, once identified, remove all infected material as soon as possible. The infected material should then be burnt, or hot composted to stop any spread. This will reduce the chance for the disease to spread.
As a producer of plant fertilisers, it seems somewhat bias that I would say that the right plant food can prevent pests and diseases. However there is truth (and a little advertising!) in this. One of the most important things you can do to prevent the majority of pests and diseases is to have strong healthy plants. Healthy plants are much more able to use their own natural defences to resist P&D, and are likely to survive for longer compared to a weaker/sicker plant. So using a balanced fertiliser with a full range of secondary and micro-nutrients to maintain healthy plant growth is strongly recommended.
As well as general health there are a few nutrients that can help a plant to build stronger defences. Silicon (often in the form of silicic acid and Potassium Silicate, its Potassium salt) can be added to all feeding regimens to increase strength throughout the plant. Not only will this reduce the chances of stems snapping under the weight of a heavy fruit such as tomatoes, but it makes it a lot harder for sap-sucking insects (such as aphids) to penetrate the plant. Furthermore the plants become more resistant to extreme of temperature and drought. Plant Magic sell Bio-Silicon for using a soil-based mediums or with hand watering and Hydro Silicon for use in Coco and Hydroponic growing set-ups. This combines available silicon with bio-stimulants to improve the uptake of the silicon.
In nature plants often form symbiotic relationships with other organisms. A symbiotic relationship is where two organisms benefit from living together for nutrition or protection. Plant roots can be protected from soil-borne pathogens by forming a symbiotic relationship with a beneficial fungi such as Mycorrhiza. The fungi covers the roots, protecting them whilst taking carbohydrates from the root for nourishment. Plant Magic Granules are a blend of Mycorrhiza, Trichoderma (another beneficial fungi) and bio-stimulants that will help protect your plants root system.
The above ground parts of the plant can be protected from fungal spores and airborne pathogens using biofilms created by friendly bacteria and other microbes. These can both combat, and impede botrytis (black mould) and leaf spot fungus. Essence from Plant Magic has a consortium of beneficial microbes to protect a range of plant types and growing environments and contains a microbial feedstock that will allow it to thrive straight away.
Ultimately all these preventative measures are subject to observation and care of your plants. A regular inspection of your plants is key to look for signs of deficiencies, pests, diseases and to keep a check on temperatures, humidity and ventilation. The sooner a problem can be identified, the better chance there is of stopping pests and diseases from causing damage.
Here at Plant Magic, we work hard behind the scenes to provide you with the nutrients, additives and growing media to help you get the most out of your plants. But successful horticulture is more than just chemicals, that's why we're using this blog to provide you with the insights, tips and techniques to give your garden that magic touch.
If you have a question about a product of ours, or you want to know more about any part of the growing cycle from propagation to harvest, why not contact us via the contact form or get in touch on social media and your question could form part of our next blog. Alternatively we have a list of the most frequently asked questions in our FAQ section.
Search through our previous blog posts by month.View All