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Pest, Disease & Root Zone Management

Pests and root disease spread fast in the warm, still air of an indoor grow room, and correct identification matters more than any single treatment product. These guides cover identifying and treating the pests and diseases most common in Australian indoor grows, spider mites through to root rot, along with the prevention habits that stop them establishing in the first place.

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How Accurate Are Plant Disease Identification Apps?
Plant ID apps drop from 76% to 31% accuracy outside lab conditions. Why grow tents are the hard case, and what a photo can never tell you about a hydroponic problem. Read more...
Overwatering Doesn't Exist in Hydroponics: Root Zone Oxygen, Dry-Back and Why DWC Works
Overwatering is soil advice that does not survive contact with hydroponics. DWC roots sit in water permanently and thrive. Here is what actually matters at the root zone, and why feeding more often is usually the fix rather than the cause. Read more...
Silica in Hydroponics: What It Does, Which Form to Use, and How to Add It Correctly
Quick Answer Silica strengthens cell walls, thickens stems, and builds a physical barrier against pests, heat stress and fungal pathogens. Potassium silicate needs the plant to convert it before use, mono silicic acid is already in a form roots can absorb directly. Add silica to your reservoir before anything else, it needs to dilute before your base nutrient goes in or it can react and precipitate out of solution. Research backs the pest-resistance claims for spider mites specifically, the picture is weaker for thrips and silica does nothing for fungus... Read more...
Why Is My Hydroponic Plant Wilting Even Though It Has Water?
Plenty of water but the plant's still wilting? Here's why roots stop taking up water even when it's right there. Read more...
Botrytis (Grey Mould) in Hydroponic Flowering Plants: Identify, Treat and Prevent
Quick Answer: Botrytis Prevention and Treatment Botrytis (grey mould) needs high humidity and dead or dying plant matter to establish, unlike powdery mildew it cannot germinate on dry, healthy tissue. Dense flower clusters on tomatoes, strawberries and other fruiting or flowering crops trap moisture at the centre, this is where botrytis almost always starts. Keep humidity below 50% during late flowering or fruiting, botrytis risk rises sharply above 60% RH combined with still air. Remove dead leaves, spent flowers and any damaged plant tissue promptly, decaying matter is the entry... Read more...
Aphids on Hydroponic Plants: How to Identify, Treat and Prevent an Infestation
Quick Answer: Aphids on Hydroponic Plants Australia Aphids are soft-bodied sap-sucking insects that cluster on new growth, stem tips, and the undersides of leaves. They reproduce without mating and a single aphid can produce 80 offspring in a week, making early identification critical. Most hydroponic aphid infestations enter through intake fans, infected clones, or clothing and hands. Neem oil, Zero Tolerance, and pyrethrum-based sprays are the most effective botanical treatments available in Australia. Aphids excrete honeydew which promotes sooty mould growth on leaves and bud surfaces, creating a secondary problem.... Read more...
Scale Insects on Plants: How to Identify, Treat and Prevent in Australia
Quick Answer: Scale Insects on Plants Australia, Identification and Treatment Scale insects are sap-feeding parasites that appear as small bumps or waxy coatings on stems and leaf surfaces. Easy to miss early. Soft scale produces honeydew and sooty mould. Armoured scale does not. The type determines which treatments are effective. Their protective coating makes them resistant to most spray treatments. The key is direct contact with the insect body. Horticultural oil or insecticidal soap suffocates scale by coating their bodies. Apply thoroughly and repeat at 7 to 10 day intervals.... Read more...
Thrips on Hydroponic Plants: How to Identify, Treat and Prevent in Australia
Quick Answer: Thrips on Hydroponic Plants Australia Thrips are 1 to 2mm insects that cause silvery streaking and distorted leaf growth, and adults can fly, making containment harder than spider mites. Look for silvery or bronze streaking on upper leaf surfaces and black faecal deposits on the undersides, the first visible signs. Thrips larvae feed inside leaf tissue during their pupal stage in the growing medium, so treating only adults misses the larval cycle. Apply treatments during lights-off and directly to leaf undersides where larvae feed, since coverage of undersides... Read more...
Spider Mites in Australian Grow Rooms: How to Identify, Treat and Prevent
Quick Answer: Spider Mites in Australian Grow Rooms Spider mites are arachnids not insects, so most insecticides won't work against them. First signs: tiny pale or yellow speckling on the upper leaf surface. Always check undersides of leaves first. Above 27C their lifecycle completes in as little as 5 days, and Australian summers dramatically accelerate this. Rotate treatment products every application to prevent resistance building in the mite population. Always spray during lights-off to avoid burning already-stressed leaves. Remove and dispose of heavily infested leaves before treating, rather than attempting... Read more...
How to Get Rid of Fungus Gnats in Hydroponics: Identification, Treatment and Prevention Australia
Quick Answer: How to Get Rid of Fungus Gnats in Hydroponics Australia Fungus gnats (Bradysia spp.) are 3 to 4mm dark flies, where adults are a nuisance but larvae in the medium cause the real damage. Larvae feed on roots and fungal growth in moist media, causing wilting, yellowing, and damping off in seedlings. Let the top layer of growing media dry between irrigations, since larvae cannot complete their lifecycle in dry conditions. Gnat Nix top dressing kills larvae on contact and remains effective when wet, unlike diatomaceous earth. Bti... Read more...
Diatomaceous Earth for Fungus Gnats: Does It Work in Hydroponics?
Quick Answer: Diatomaceous Earth for Fungus Gnats in Hydroponics Diatomaceous earth stops working the moment it gets wet, it is unreliable as a fungus gnat treatment in hydroponic systems. DE kills by physical abrasion to insect exoskeletons, this mechanism fails when the powder clumps with moisture. Gnat Nix is the proven alternative, a physical top-dressing made from recycled glass that stays effective when wet. Bacillus thuringiensis var. israelensis (Bti) products like Gnat Off target larvae in the growing medium with biological precision. Sticky yellow traps catch adult fungus gnats and... Read more...
Neem Oil for Hydroponics: How It Works and Which Pests It Solves
Quick Answer: Neem Oil for Hydroponics Pest Control Australia Neem oil's active compound azadirachtin disrupts pest moulting, suppresses feeding, and degrades reproductive cycles simultaneously. Neem oil is most effective as a preventative and early-stage treatment, it does not kill adults on contact as reliably as some alternatives. Always apply during lights-off and let the foliage dry before lights come back on, oil on leaves under light causes burn. Cold-pressed neem oil contains more azadirachtin than clarified or processed versions, check the product specification before buying. Do not apply to open... Read more...
Mealybugs on Hydroponic Plants: How to Identify, Treat and Prevent in Australia
Quick Answer: Mealybugs on Hydroponic Plants Australia Mealybugs are covered in white waxy powder and produce cottony egg masses, easily mistaken for natural plant features in early infestations. They feed by piercing tissue and extracting sap, causing yellowing, wilting, distorted growth and sticky honeydew residue. Their waxy coating protects against many spray treatments, so contact sprays must reach the insect body directly to be effective. Isopropyl alcohol at 70% on a cotton swab applied directly to individual mealybugs dissolves the wax and kills on contact. Repeat treatment is essential, since... Read more...
Pest Infestation in Hydroponics: How to Identify, Treat, and Prevent Common Grow Room Pests
Quick Answer: Hydroponic Pest Infestation Signs, Causes and Treatments Early detection is critical, since stippling, bronzing, sticky residue, or distorted growth are easier to treat before populations explode. Indoor grow rooms create ideal pest conditions: warm temperatures, dense canopies, no natural predators, and consistent humidity. Inspect plants twice per week minimum, focusing on undersides of leaves, root zones, and growing media surfaces. Root aphids are the most commonly misdiagnosed pest, they look like a stubborn nutrient deficiency and need a root zone drench, not a foliar spray. Quarantine all new... Read more...
Powdery Mildew in Grow Rooms: Causes, Prevention and Treatment
Quick Answer: Powdery Mildew Prevention and Treatment PM spores are present in ambient air everywhere, you cannot exclude them, only prevent the conditions they need to establish. Four entry points: intake fan air, infected clones, clothing and hands, and cross-contamination from other plants. PM thrives when humidity fluctuates and airflow is stagnant, consistent RH and oscillating fans are your most effective prevention. Keep humidity below 50% in late flower, PM establishes most aggressively when humidity rises above 60% in warm conditions. Treat at first sight, don't wait, PM spreads exponentially... Read more...
Root Rot in Hydroponics Australia
Quick Answer: Root Rot in Hydroponics Australia Root rot is almost always caused by Pythium, an oomycete not a fungus, so antifungal products are largely ineffective. Healthy roots: white or cream, firm, faint earthy smell. Infected roots: brown, slimy, fishy or sewage-like odour. Reservoir above 22 degrees Celsius reduces dissolved oxygen. Above 26 degrees Pythium can establish within 24 to 48 hours. Stages: early (brown root tips), established (brown slime on main roots), advanced (root mass collapse and canopy wilting). Treatment: drop reservoir temperature immediately, increase aeration, trim dead root... Read more...