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Types of Plant Disease

Posted in Garden Advice on November 10, 2014

Plant Diseases 

Plants are susceptible to disease. Many of the plants we grow in our garden have been bred for traits that we desire, such as flowers, large fruit, good flavour and shape. Sometimes this breeding process has reduced the plant’s immune system and the gardener must be pro-active in providing additional protection from disease.

Here are some different types of diseases found in New Zealand gardens.

Fungal Disease

Fungal diseases reduce crops and flowering, stress plants, cause unsightly marking and can ultimately kill your plants.

Fungi, including blackspot, rusts and mildews will, given the chance, attack our fruit trees, roses, vegetables and ornamental plants. Lawns can be attacked by various fungal diseases including brown patch, red thread, midlews, slime moulds, leaf spot, smuts and blights.  Explore more fungal diseases on the Kiwicare Problem Solver.

Kiwicare produces a comprehensive range of fungicides and combination fungicide/insecticides and disease protective products to help you keep your plants healthy, productive and beautiful.

Bacterial & Viral Disease

Other than fungi, plants are also vulnerable to disease caused by bacteria and viruses. PLANThealth Copper Fungicide Liquid and Organic Super Sulphur will protect from bacteria and fungi.

The best way to prevent vial disease is to keep your plants healthy so that they are not damaged and their own immune system is able to ward off viruses.

Nutrient Deficiency

Not all disease is caused by other organisms. Sometimes the plant is diseased because it is deficient (or over supplied) with some nutrient.

Water is a very obvious example of where a lack of or an over-abundance is detrimental. Plants with too little water rapidly show symptoms of dehydration and wilting. Without water moving up from the roots to supply the stems and leaves there is also the problem of a lack of the nutrients that would travel with the water. The leaves will often begin to yellow and eventually go brown.

The same is true when the root system is waterlogged. The plant is unable to transport nutrients properly and again the leaves will often yellow, droop and die.

Even with a good water supply if the soil does not contain the nitrogen, phosphorus, potassium and other chemicals that the plant needs to function properly it will sicken, become weak and susceptible to disease caused by fungi, bacteria and viruses.

Product Actives Systemic/ curative Contact/ preventative Effective Against Plants Registered for use on Crops? Other Benefit
PLANThealth Fungus Control Boscalid, Pyraclostrobin, Tebuconazole Yes Yes Powdery mildew, downy mildew, rust, blackspot, rots, root rot, dieback Roses, ornamental No Multiple actives help prevent resistance development.
Rose Force Discontinued Azoxystrobin, Thiocloprid Yes Yes Powdery mildew, downy mildew, rust, blackspot, rots Roses, ornamentals No Systemic and contact action for both insecticide and fungicide
Spectrum Myclobutanil, Tau-fluvalinate Yes Yes Powdery mildew, rust, black spot, scab Roses, ornamentals No Plus contact insecticide
Thiram Fungus Control
Thiram   Yes Botrytis, brown patch, dollar spot, fusarium Fruit trees, soft fruit, ornamentals, shrubs, roses, lawns Fruit trees, vegetables  
LawnPro Fungus Control Thiram   Yes Red thread, brown patch, dollar spot, fusarium, pythium Lawns No  
Root Protect Aliette
Fosetyl-aluminium Yes Yes Root rot, dieback, downy mildew, Buxus blight Fruit trees, vegetables, ornamentals, roses Fruit trees  
Buxus Blight Buster
Fosetyl-aluminium Yes Yes Buxus blight, downy mildew, Phytophthora, Pythium Buxus, ornamentals, roses No Upwardly and downwardly mobile
Buxus Blight Buster Thiram   Yes Buxus blight, downy mildew, Phytophthora, Pythium Buxus, ornamentals, roses No  
Organic Super Sulphur Sulphur   Yes Powdery mildew, rust, scab, brown rot, rose blackspot Fruit trees, vegetables, roses Fruit, vegetables Helps control spider mites
Organic Super Spraying Oil Mineral oil   Yes Powdery mildew, viruses Roses, fruit trees, citrus, ornamentals Fruit trees Also controls insects.
Use as part of winter spraying program with Copper and Super Sulphur.
PLANThealth Copper Fungicide Liquid Copper   Yes Fungal and bacterial diseases Roses, fruit trees, citrus, ornamentals Fruit, vegetables Use as part of winter spraying program with Oil and Super Sulphur.

David Brittain

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