DISEASE

NAME
Ringspot (General)
Various Ringspot Viruses

Description
This is a viral problem that normally affects the leaves of plants.

Symptoms
Ringspots affects leaves by forming small chlorotic or necrotic greenish or brown spots with pale green rings, giving a simular appearance to a nutrient deficiency. The plant becomes stunted and the affected leaves turn yellow and die.

Camellia japonica     

Palm Ring Spot(Bipolaris incurvate) has distinct brownish spots that are surrounded by yellowish rings. Heavy infection turns the leaves yellow causing them to die.

Palm Ring Spot(roystonea palm potyvirus) forms ring spots that become necrotic or chlorotic spotting on the new growth. Affected plants become stunted and die prematurely. Affected plants include; Roystoneaand Chamaedoreaspecies.
          
Source and Dispersal
The virus is derived from other infected plants or dispersed by sap sucking insects such as aphids or leaf hoppers. Corms, bulbs or tubers are commonly infected and the virus is spread by propagation material. These viruses are found from tropical to temperate climates.

Favoured Conditions
The viruses varies as some occur with out any documented favoured conditions, but certain viruses such as the Palm Ring Spot are more prevalent in hot wet conditions, especially when the plants are growing close together.

Affected Plants
Many plants are infected by Ringspots including; Camellia Japonica, Cichorium intybus, Howea and other palm species and perennials.

Carica papaya(Pawpaw) is infected by the Papaya Ring Spotwhich causes blemishes on fruit and leaves.

Pawpaw fruit

Delphiniumspecies are infected by the Ringspot (Annulus delphinii) which causes chlorotic spots that may be encircled by yellow rings.

Gladiolusspecies are infected by the Tobacco RingspotVirus (Annulus tabaci). It attacks the foliage and flowers causing stunting and fading of colours.

Non-chemical Control
Plants cannot be cured of this disease and it is important to maintain healthy mother stock for propagation by isolating it from infected stock. Infected leaves and plants should be removed and destroyed. When planting allow adequate spacing to allow good air circulation to reduce humidity and avoid handling the plants. All tools should be sterilised to minimise transferring infections.

Chemical Control
There is no chemical control for viral diseases but the use of the appropriate chemical control of sap sucking insects, such as aphids is advised.
Note
Always read the label for registration details and direction of use prior to application of any chemicals.