Diseases and pests

Diseases and pests
Rust is caused by a fungus and is visible as orange, reddish-brown or blackish-brown spots. The discoloration is a reaction of the affected leaves to the fungal infection. This disease mainly occurs when the weather is warm and moist.
Preventing and controlling rust is rather difficult. When rust is discovered in an early stage, you can reduce spreading by removing the affected leaves and/or parts of the plants. Further spreading can be prevented by being careful when watering the plants. Water the plants at the root and make sure the (infected) leaves do not get in contact with the water.
Biological control is possible with compost-tea (soak compost mixture in water), this has to be used several times to fight rust. Grasses that are sensitive to a rust infection are a.o. Carex panicea, Calamagrostis brachytricha, Calamagrostis acutiflora ‘Karl Förster’, Calamagrostis acutiflora ‘Overdam’, Calamagrostis acutiflora ‘Avalanche’, Deschampsia cespitosa and Helictotrichon sempervirens

Plant lice can cause a yellow discoloration of some plants (Carex comans ‘Frosted Curls’) or slow growth.There are several biological pesticides for lice. For instance Ecostyle Spruzit-R.Lice mainly occur on Carex comans ‘Frosted Curls’, Carex comans ‘Bronze Form’, Carex buchananii, Carex caryophyllea ‘The Beatles’, Carex elata ‘Aurea’ and Stipa tenuifolia.

Leaf spot disease is a fungal attack and occurs when the weather is moist and warm. Specific to this disease are brown spots with a yellow edge and at the bottom of these spots there often a green to brown fungal fluff can be found. The affected leaves usually falls off. Spreading from plant to plant is done by (rain) water and in the plant itself the fungus is transported through the vascular bundles.
Measures that can be taken are for instance:

  • Regularly removing the leaf residues;
  • Careful watering, preferably water at the roots of the plant so the water does not get into contact with the contaminated leaves;
  • To curtail the disease you could treat the plant with the fungicidal product Sporgon, a retreatment after three weeks increases the results.
  • Leaf spot disease often occurs on Carex comans ‘Snowline’, Carex oshimensis ‘Evergold’ and Hakonechloa macra ‘Aureola’.