Overturning disease
Symptoms:
- Stem becomes thin and plantlet eventually bends
Problem
Falling sickness is usually caused by a fungal disease. The cause is contaminated soil, too wet substrate or too high humidity. The fungus attacks the soft tissue in the stem, which dries out at the base or halfway. The seedling collapses and dies. Another possible cause can be too little water or salinated soil.
see also Falling sickness - cause and prevention
Remedy
- Clean and disinfect all grow utensils
- ensure good ventilation
Boron deficiency
Symptoms:
- abnormal or thick plant tips
- Yellowing of new leaves
- new shoots look like burnt
Problem
Boron deficiency: The leaves and roots look abnormal and the growth of the plant slows down. First signs are very thick shoot tips and a rough stem, there may be yellowing of new leaves. Boron deficiency is easily confused with calcium deficiency, as the plants need boron to use calcium properly. New shoots are most affected by a boron deficiency and look like they have been burnt or singed. If the plant does not have enough potassium or nitrogen or the pH is not right, it cannot absorb boron.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose.
- Increase potassium and/or nitrogen
Calcium deficiency
Symptoms:
- Leaves are mottled, have dead spots
- new leaves become smaller and curl
- Flowers "disintegrate
- stunted roots
Problem
Calcium deficiency: Calcium deficiency is often accompanied by magnesium, iron and other deficiencies. Mostly calcium deficiency occurs due to a faulty pH-value, as the roots cannot absorb the calcium. However, there are some cannabis strains that need a lot of calcium.
Remedy
- Check pH value and adjust if necessary
- possibly add Ca-Mn preparations
Manganese deficiency
Symptoms:
- Leaves yellow between the veins
- mottled brown spots
- Leaves die, decay
- stunted growth
Problem
Manganese deficiency: Manganese deficiencies are often caused by a too high pH-value. Another cause can be an excess of iron.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose.
- In future, use water with the correct pH value.
Molybdenum deficiency
Symptoms:
- Yellowing of the leaves with orange, red or pink edges
Problem
Molybdenum deficiency: The cause is usually too low a pH value, so that the roots cannot absorb molybdenum.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose.
- In future, use water with the correct pH value.
Nitrogen surplus
Symptoms:
- dark green leaves
- Eagle claws, leaves curl in at the edges
- Leaves wither and fall off
Problem
Excess nitrogen (N): Too much nitrogen shows up in very dark green leaves that bend the tips downwards, so-called "eagle claws". Too high temperatures and the wrong pH-value aggravate the problem. Too much nitrogen leads to an undersupply of the plant with other vital substances.
Remedy
- rinse the plant with pure water with pH 5.5-6.5
- Reduce nitrogen application
Burns due to overfertilisation
Symptoms:
- Leaf edges look burnt
Problem
Burns due to overfertilisation: If only the tips of the leaves are discoloured, this is usually not a problem. However, if larger areas are affected, be sure to rinse the plants with clear water and continue to feed them with only a small amount of fertiliser.
Remedy
- rinse the plant with pure water with pH 5.5-6.5
- Water only with a small amount of fertiliser over the next few days and increase the amount slowly.
Phosphorus deficiency
Symptoms:
- Growth retardation
- dark grey, purple spots
Problem
Phosphorus deficiency: Plants need phosphorus for growth and especially for flower formation. Phosphorus deficiency occurs mainly when there is an iron (Fe) or zinc (Zn) surplus. The plants can then not absorb enough phosphorus.
More information about phosphorus in growing can be found here here.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose.
- Increase phosphorus quantity
Potassium deficiency
Symptoms:
- older leaves first turn yellow and get burnt edges
Problem
Potassium deficiency: Potassium deficiency is caused by an incorrect pH value or an excess of calcium or nitrogen, the plants can then not absorb enough potassium.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose.
Copper deficiency
Symptoms:
- Leaves curl
- Growth retardation
- unusual leaf colours
Problem
Copper deficiency: A copper deficiency usually manifests itself in curled back leaves with unusual discolouration (from white to pink to blue) and very slow growth. The cause is almost always an incorrect pH value of the watering water.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose.
Sulphur deficiency
Symptoms:
- Yellowing of the leaves
- Discolouration starts at the leaf style and moves to the tips
Problem
Sulphur deficiency: Sulphur deficiency looks like nitrogen deficiency at first glance. The difference is that with sulphur deficiency the leaves change colour starting from the leaf style, with nitrogen deficiency the fading starts at the leaf tips. The reason for a sulphur deficiency is usually an incorrect pH value of the watering water.
Remedy
- rinse the plant with pure water with pH 5.5-6.5
Zinc deficiency
Symptoms:
- Yellowing between the leaf veins in young leaves
- Leaf tips turn brown and die off
- less space between the internodes, the leaves grow into each other
Problem
Zinc deficiency: Zinc deficiency can be recognised by the only short internode distances. As a result, they start to tangle the new leaves, yellowing begins between the leaf veins. The cause of a zinc deficiency is usually an incorrect pH value of the watering water, so that the plant cannot absorb zinc.
Remedy
- Rinse the plant with a nutrient solution with pH 5.5-6.5 and half the fertiliser dose (incl. zinc, iron and manganese).
Too little water
Symptoms:
- Leaves limp and lifeless
Problem
Too little water: if the plants do not get enough water, they start to droop their leaves and look lifeless. It is important to provide the plants with enough water/nutrient solution on a regular basis. A good trick is to water your plants when the pot feels only slightly heavier than a comparable pot with dry soil.
Remedy
- Water plants sufficiently with nutrient solution
Overwatering
Symptoms:
- Leaves droop and curl
- Leaves yellow
Problem
Overwatering: If the plant has been/is overwatered, its roots are in water and can no longer absorb oxygen. There is also a lack of nutrients. Often overwatering occurs when you use pots that are too big, because the roots cannot completely remove the water.
Remedy
- Allow the planting medium to dry and start again with the correct amount of water
too much heat, burns
Symptoms:
- yellow leaves with brown spots
- Burns on the leaves
- Leaf margins die
Problem
Burns from the lamp / too much heat: If the plants are too close to the hot lamp or there are too hot spots in the growroom, the plant can get burned. If the temperature is too high, the leaf edges will dry out first and die.
Remedy
- Lowering the temperature in the growroom
- Increase the distance of the plants from the lamp
Phythium / root rot
Symptoms:
- brown roots
- Root system smells rotten
- Plant loses leaves quickly
- Plant hardly absorbs any water
- the lower part of the trunk turns brown
Disease
Phythium / root rot: Phythium and root rot are caused by bacteria in the water and especially by overwatering or waterlogging. Affected roots will not recover, but new root growth can be produced. It is absolutely necessary to treat the roots as well as to change the watering behaviour and/or to provide sufficient drainage.
Remedy
- Lowering the temperature in the growroom
- Increase the distance of the plants from the lamp
Salinisation of the substrate
Symptoms:
- yellowed leaves
- Leaves fall off
- thin stems
Problem
Salinisation of the substrate: Especially when fertilising with mineral fertilisers, care should be taken to flush the plants regularly. Otherwise the plant substrate will become saline and the plants will no longer be able to absorb water and nutrients through their root system.
Remedy
- rinse the plants with pure water with pH 5.5-6.5
Botrytis
Symptoms:
- Flowers turn grey inside and decay
Disease
Botrytis: Botrytis or grey mould mainly affects dense, compact flowers towards the end of the flowering phase. Indicas are more affected than sativas because of their flower shape.
More on the topic Botrytis
Powdery mildew
Symptoms:
- white, powdery coating on the leaves
Disease
Powdery mildew: Powdery mildew is a mould disease that can occur as true and downy mildew. If mildew is not treated, it can develop into botrytis. Powdery mildew also develops at low humidity.
More on the topic Powdery mildew and its control
Remedy
- Treatment with UV light
- Ensure sufficient ventilation
- spray with a solution of 2/3 water and 1/3 milk
Note: It is normal for the leaves to turn yellow towards the end of the flowering period, so do not increase the amount of nitrogen (N) you give your plants. During the last few weeks before harvest, the plant will extract any remaining sodium from its leaves as part of the flowering process. This leads to yellow leaves and is part of the natural flowering phase. Increased sodium during flowering will result in dark green leaves, but also smaller buds!
Mineral deficiencies often occur due to an incorrect pH value! The gardener wonders how a deficiency can arise even though fertiliser has been
fertiliser schedule. Often a wrong pH-value is responsible for this. Read and learn more about this in our article: the optimal pH value.
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