Pests and Nutrient Deficiencies

Spot the symptoms early: pests, fungal diseases and nutrient deficiencies when growing cannabis.

Quick overview

SHIVA Surface Cleaner

Problem	Type	Frequency	Where to look first
Two-spotted spider mite	Animal pest	Very common	Leaf undersides, shoot tips
Thrips	Animal pest	Very common	Young leaves, leaf surface
Aphids	Animal pest	Common	Young shoots, leaf undersides
Whitefly	Animal pest	Common	Leaf undersides
Fungus gnats	Animal pest	Common	Surface of the growing medium
Powdery mildew	Fungal disease	Very common	Leaf surface
Botrytis	Fungal disease	Very common	Inside dense buds
Downy mildew	Fungal disease	Less common	Upper and lower leaf surfaces

SHIVA Surface Cleaner: the "Plant care – leaf wash" sections above describe only the role of regular leaf washing with SHIVA Surface Cleaner. Leaf washing is a care routine that helps keep plant surfaces clean – it does not replace an accurate diagnosis and should not be regarded as a sufficient solution on its own against any pest or disease. On flowering plants, avoid soaking dense buds for long periods; after washing, the surface must dry completely.

Pests and fungal diseases

In indoor cannabis growing, the enclosed environment can encourage some pests to multiply quickly and certain fungal diseases to develop. Early detection requires regular checks of the upper and lower leaf surfaces, the young shoots and the buds.

Two-spotted spider mite Very common

Tetranychus urticae

One of the most common indoor pests. It multiplies quickly in warm, dry conditions and can damage a large leaf area in a short time.

Tiny pale feeding spots on the leaves; fading or bronzing leaf surface; fine webbing on the leaf undersides and between the shoots; with a heavy infestation, leaves dry out and drop.

A warm, dry grow space, infested cuttings or new plants, infrequent checks of the leaf undersides.

Cannabis, peppers, tomatoes, cucumbers, roses and many ornamental plants.

Regular, thorough washing of the leaves – especially the undersides – is recommended. When using SHIVA Surface Cleaner, aim to wet the entire leaf surface evenly.

Thrips Very common

Frankliniella occidentalis and other Thripidae species

Tiny, fast-moving insects. By damaging the surface cells of the leaf, they leave characteristic silvery scars and streaks.

Silvery or bronze streaks and patches; tiny black specks of excrement; distorted young leaves; slower growth.

Infested propagation material, a warm and enclosed growing environment, dense foliage that is hard to inspect.

Cannabis, peppers, tomatoes, cucumbers and many ornamental plants.

Regular washing of the upper and lower leaf surfaces is recommended. When using SHIVA Surface Cleaner, also pay attention to the areas next to the leaf veins and to the young leaves.

Aphids Common

Aphididae

Fast-breeding, colony-forming sap-sucking pests that appear mainly on young shoots and the undersides of leaves.

Visible aphid colonies; distorted, cupping young leaves; sticky honeydew on the leaf surface; stunted growth.

Infested new plants, dense shoot growth, infrequent checks of young plant parts.

Almost all horticultural crops, including cannabis.

Regular washing should focus especially on keeping young shoots and leaf undersides clean. SHIVA Surface Cleaner can help remove accumulated honeydew and other surface deposits.

Whitefly Common

Trialeurodes vaporariorum and Bemisia tabaci

Tiny sap-sucking insects with white wings. The adults often fly up when the plant is moved, while their immature stages are found on the leaf undersides.

White insects that fly up; yellowing leaves; sticky honeydew; a dark surface coating forming on the honeydew.

A warm growing environment, dense foliage, infested propagation material.

Cannabis, tomatoes, peppers, cucumbers and ornamental plants.

Regular, even washing of the leaf undersides is recommended. Using SHIVA Surface Cleaner can help keep the leaf surface clean and remove sticky deposits.

Fungus gnats Common

Bradysia spp. and other Sciaridae species

The adults are tiny dark flies that usually fly around moist growing media. The larvae develop in the medium.

Tiny black flies around the pots; slow growth; weakening of young plants; in severe cases, wilting that points to root damage.

Constantly moist growing medium, organic residues on the surface of the medium, a high-humidity environment.

All plants grown in pots and growing media.

Leaf washing with SHIVA Surface Cleaner supports the surface hygiene of the plant, but it does not directly prevent larvae developing in the medium – here the product is useful only as a general plant-care leaf wash.

Powdery mildew Very common

Golovinomyces spp. and other powdery mildew fungi

An easily recognisable fungal disease that develops on the leaf surface. At first, small white spots appear, which can later merge into a continuous coating.

White, flour-like spots or coating; fading, distorted leaves; reduced photosynthetic leaf area; in advanced stages, the leaves dry out.

High or strongly fluctuating humidity, poor air movement, dense foliage, infected plant material.

Cannabis, hops, cucurbits, grapevines, roses and many other plants.

Regular washing helps keep the leaf surface clean. Leaf washing is a care routine – it does not eliminate an infection that has already developed.

Botrytis (grey mould) Very common

Botrytis cinerea

One of the most significant fungal diseases of flowering cannabis. It often starts inside dense buds, so it is hard to spot at first.

Browning or dying flower parts; greyish mould; soft, rotting tissue; the affected part comes away or falls apart easily.

High humidity, persistent moisture, poor air movement, dense buds and damaged plant parts.

Cannabis, grapevines, strawberries, tomatoes, peppers and many flowering plants.

Recommended for keeping the vegetative leaf surface clean. Soaking dense buds directly and heavily is NOT recommended, as trapped moisture can increase the risk.

Downy mildew Less common

Peronospora, Pseudoperonospora and Plasmopara spp.

Less common in indoor cannabis, but downy mildew-like symptoms can develop when the leaf surface stays wet and humidity is high.

Yellowish patches on the upper leaf surface, often bounded by the veins; a greyish-purple coating on the leaf underside; browning, dying leaf areas; in advanced stages, leaf drop.

Persistent leaf wetness, high humidity, cooler night periods, poor air movement.

Grapevines, cucumbers, lettuce, onions, basil; less common in cannabis.

Regular cleaning of the leaf surface can be part of good hygiene. After application, the leaves must dry completely – never keep foliage wet for long periods.

Nutrient deficiency table

Plants need micro- and macronutrients in small amounts, but a deficiency can cause serious yield losses. Recognising the visual symptoms is key to acting early.

Macronutrients

Nitrogen

A main component of chlorophyll and proteins. Stimulates vigorous leaf and shoot growth. Crucial in the vegetative stage.

Deficiency symptomsThe lower leaves turn yellow first, then it spreads upwards. Slow growth, pale foliage.

Phosphorus

Root development, flowering and energy transfer (ATP). Critical during flowering and fruit set.

Deficiency symptomsPurplish-red discolouration of the leaves, especially on the undersides. Slow flowering, weak root system.

Potassium

Water and nutrient transport, turgor, disease resistance. Especially important in the final stage.

Deficiency symptomsLeaf edges turn brown and dry out. Weak stems, reduced resistance.

Calcium

Cell wall formation, root growth, nutrient uptake. Immobile in the plant – needs a continuous supply.

Deficiency symptomsYoung leaves become deformed and brown spots appear. BER (blossom-end rot) in tomatoes and peppers.

Magnesium

The centre of the chlorophyll molecule. Supports photosynthesis, enzyme activity and phosphorus uptake.

Deficiency symptomsInterveinal chlorosis: the veins stay green while the tissue between them turns yellow. Appears on older leaves.

Sulphur

A building block of amino acids and proteins. Enzyme activator, supports terpene production.

Deficiency symptomsEven yellowing of young leaves (starting from the top). Slow growth.

Micronutrients (trace elements)

Iron

Chlorophyll synthesis, nitrogen fixation, enzyme component. EDDHA chelate is insensitive to pH.

Deficiency symptomsYoung leaves turn yellow while the veins stay green. Most common cause: alkaline soil (pH>7).

Manganese

Chlorophyll synthesis, vitamin C and nitrogen metabolism. More mobile in acidic soil.

Deficiency symptomsInterveinal chlorosis on young leaves, alkaline soil. Pale appearance, slow development.

Zinc

Component of enzyme systems, protein synthesis, production of growth hormones.

Deficiency symptomsShort internodes, small leaves, yellowing and mottling. Late ripening.

Copper

Reproduction, enzyme activity, chlorophyll synthesis. Supports root development and protein utilisation.

Deficiency symptomsYoung leaves turn yellow, then die. In extreme cases the leaves shrivel.

Boron

Cell membranes, root and shoot growth, sugar transport. Critical during fruit set.

Deficiency symptomsMore common on alkaline soil. Dieback of growing tips, deformed leaves, bud drop.

Molybdenum

Nitrogen metabolism, protein synthesis, conversion of inorganic phosphates into organic forms.

Deficiency symptomsTypical on acidic soil. Pale, deformed leaves, slow growth.

Plants obtain carbon, hydrogen and oxygen from the air and water – these make up most of the plant's biomass. Alongside the 13 nutrients, they are also essential.

The SHIVA solution: SHIVA Boost, Grow and Bloom contain a chelated micronutrient package, and Grow and Bloom also contain added EDDHA iron – the chelated fraction is stable between pH 3 and 9 and immediately available. If you see deficiency symptoms, always check the pH first!