Weekly Report

20 September 2024

City
Overall Risk
Tree Pollen
Grass Pollen
Weed Pollen
Mould Spores

Summary

The highest tree counts with a large variety in species occurred in Bloemfontein where the dominant trees were false olive, or butterfly bush, plane, white stinkwood, birch and pine. Plane is the dominant tree at many sites now.

Cape Town

Tree pollen continued its release cycle and the dominant tree this week was plane. Other trees included cypress (Cupressaceae), white stinkwood (Celtis), pine (Pinaceae), yellowwood (Podocarpaceae), karee (Rhus/Searsia), ash (Fraxinus and oak (Quercus). Weeds were the daisy family (Asteraceae), mallows (Malvaceae), erica (Ericaceae), the carnation family (Caryophyllaceae), mugwort (Artemisia), sorrel (Rumex) and sedges (Cyperaceae). Grasses are appearing in the air in low concentrations and moulds are low.

Johannesburg

High tree concentrations included the dominant trees plane (Platanacaeae), white stinkwood (Celtis), sweetgum (Liquidamber), mulberry (Moraceae) and oak (Quercus). Other trees included Australian pine (Casuarina), cypress (Cupressaceae), ebony (Ebenaceae), beech (Fagus), ash (Fraxinus), gum (Myrtaceae), pine (Pinaceae), yellowwood (Podocarpaceae), gum (Myrtaceae), karee (Rhus./Searsia) and willow (Salicaceae). Weeds were low and included pigmyweeds (Crrassulaceae), sedges (Cyperaceae) and nettles (Urticaceae) and moulds were low.

Pretoria

Tre pollen is usually high at this site, with the dominant trees being mulberry (Moraceae), white stinkwood (Celtis), pine (Pinaceae), plane (Platanaceae), poplar (Populaceae) and cypress (Cupressaceae), low weed concentrations would be slangbos (Stoebe-type) and the daisy family (Asteraceae). Grasses and moulds would be low. 4-year means are shown.

Bloemfontein

High tree concentrations were seen during this sampling week. Dominant trees were false olive (Buddleja), white stinkwood (Celtis), plane (Platanaceae), pine (Pinaceae), poplar (Populaceae), olive (Oleaceae). birch (Betulaceae) and ash (Fraxinus). Trees with lower scores were cypress (Cupressaceae), waxberry (Morella), yellowwood (Podocarpaceae), oak (Quercus), mulberry (Moraceae), the sumac family (Anacardiaceae) and elm (Ulmaceae). High numbers of pigmyweeds (Crassulaceae) were followed by low concentrations of the daisy family (Asteraceae), goosefoot (Chenopdiaceae), sedges (Cyperaceae), lily (Liliaceae) and ferns (Polypodiaceae), Grasses and moulds were low.

Kimberley

Pollen concentrations declined a little during this sampling week, but tree pollen maintained a presence in the air as mulberry (Moraceae), ash (Fraxinus), bushwillow (Combretaceae) and false olive (Buddleja) released pollen. Weeds were the daisy family (Asteraceae), goosefoot (Chenopodiaceae), mezereum (Thymelaeaceae), sedges (Cyperaceae) and the carnation family (Caryophyllaceae). Grasses were present in low concentrations as were moulds.

Durban

Trees seen at this time of year include mulberry (Moraceae), celtis (white stinkwood), ash (Fraxinus), plane (Platanaceae), yellowwood (Podocarpaceae) and acacia (Acacia-type) in low concentrations. Scanty weed pollen includes the daisy family (Asteraceae), nettles (Urticaceae), knotweed (Persicaria) and ferns (Polypodiaceae). Moulds are low. 4-year means are shown.

Gqeberha

Pollen remained low at this site. Trees included sand olive (Dodoneae). Pine (Pinaceae), yellowwood (Podocarpaceae) and karee (Rhus/Sersia). Weeds were the daisy family (Asteraceae), aloe (Asphodelaceae), ice plants (Aizoaceae), ferns (Polypodiaceae) and nettles (Urticaceae). Grasses and moulds were seen in low concentrations.

Potchefstroom

This site is not operating.

George

Tree pollen is increasing at this site. Trees included pecan (Carya), bushwillow (Combretaceae), cypress (Cupressaceae), gum (Myrtaceae), pine (Pinaceae) and poplar (Populaceae). Weeds were mugwort (Artemisia), erica (Ericaceae), goosefoot (Chenopodiaceae), mezereum (Thymelaeaceae),  ferns (Polypodiaceae) and sedges (Cyperaceae). Moulds were present in low concentrations. Last week’s findings are repeated as the spore trap was malfunctioning.

Reference Range

Grass:      Low: 0-5       Moderate:      6-20         High: 21-200

Trees:      Low: 0-15     Moderate:    16-90         High: 91-1500

Weeds:   Low: 0-10      Moderate:   10-50         High: 51-500

Moulds:  Low: 0-900    Moderate:  900-2500   High 2500-25000

Unit: per cubic metre