Whenever there's a profusion of flowering trees, grasses and even weeds, that means sneezes, runny noses and itchy eyes for many of us.
The change of seasons can be particularly trying. Up to 20% of South Africans suffer from allergic reactions, according to the Allergy Society of South Africa. This includes sneezing, wheezing and itchy eyes.
The culprit? Pollen. Trees, grass and weeds produce it in abundance in order to survive.
And for many South Africans this might spell hay fever (seasonal allergic rhinitis), asthma and eczema.
Not all pollens cause allergic symptoms. The sticky, heavier pollens produced by brightly coloured flowers and dispersed by insects or birds usually don't cause allergies. In fact the more brightly coloured the plant the less likely the chance of it causing allergies.
It's the more mundane-looking bushes - the ones that have to rely on the wind to carry pollen - that you should worry about.
There's another snag: male plants are the ones that produce pollen to fertilise the fruit of female plants yet municipalities tend to plant male trees in an effort to reduce the mess made by fruit.
What can you do?
Avoidance where possible is the most effective treatment strategy for pollen allergy, according to allergy expert Dr Harris Steinman. He advises:
Keep the windows of your home and car closed. Have a filter fitted to air vents in your home and car.
Avoid grass cuttings and direct exposure to flowering trees or flowers, and stay indoors during peak seasons (check our list).
When going for walks avoid forests or gardens where trees may be in bloom.
When gardening wear a mask and take an antihistamine tablet 30 minutes before going outside if you've ever suffered from allergies triggered by pollen. Take a shower immediately after working outside. Throw your gardening gear in the wash when you've finished.
Wear wraparound glasses or sunglasses in the pollen season. To relieve itchy eyes wash them with water to remove pollen.
If you struggle to breathe through your nose you might have nasal polyps. An antihistamine tablet on its own won't be all that useful; your doctor might prescribe an aqueous nasal steroid spray.
Mould is rife in compost heaps. Place them as far from the house as possible.
Plant insect-pollinated plants or female plants. Ask experts at your local nursery.
Don't stick your nose in a carnation, chrysanthemum or other insect-pollinated flowers. Be careful not to place your garden bench right next to flowerbeds as insect droppings may also cause allergies.
Get to know your enemy. If you know which plants are likely to make you sneeze and wheeze you can keep well away.
The main allergens
Watch out for foreign trees that produce large amounts of windborne pollen - our indigenous trees produce insect-borne pollens that are, on the whole, too sticky and heavy to be carried far by the wind.
Cypress trees , native to southeastern Europe, are found mostly in the coastal areas of the Western and Eastern Cape and are often grown as ornamental garden trees.
They have male flowers and female ligneous cones. The cypress produces large amounts of pollen from July to October.
Oak trees are not indigenous to South Africa and were brought here in the 17th century from Europe.
They're found mostly in the Western Cape and flower in spring or early summer.
Oak pollen can be problematic to allergy sufferers.
Plane trees ( London planes) are found in most urban areas of South Africa.
These foreign deciduous trees produce large amounts of buoyant pollen. The flowering season is in October and November.
The foreign eucalyptus is an evergreen found mainly in Gauteng but also scattered throughout South Africa.
It has a tendency to flower all year, especially in warmer areas. In the Western Cape its flowering season is restricted mostly to August to November.
Many acacia trees are indigenous to South Africa - the best known being the thorn trees that grow on the savannah. Many of these trees bloom in late spring and early summer.
The pollen of some can be allergenic.
The Port Jackson willow was imported from Australia and is considered an alien invader in the Western Cape.
The tree's bright yellow flowers are especially striking in spring when the pollen can cause allergies.
The huge yellowwood tree must be one of the most stately and decorative of our indigenous trees. It is a tall, straight-stemmed, evergreen forest tree with dense, glossy foliage.
It occurs mainly in the Western Cape. Its flowering season is from October to December.
Grass pollens are by far the most abundant of the pollens and a great problem for allergy sufferers in South Africa. Pollen levels peak here in summer but - unlike elsewhere in the world - grass pollens are present almost all year, especially in some parts of the country.
Grass pollen is easily inhaled because it is so small, which is a nightmare for asthma sufferers.
Bermuda grass , one of most allergenic grasses, is a creeping, low-growing green-grey grass which spreads rapidly.
It's found throughout South Africa and flowers from September to May.
Johnson grass , native to the Mediterranean, is found in the dry regions of South Africa. It's extremely allegenic and flowers from December to January.
Rooigras (red grass) grows in all areas of South Africa except the Western and Northern Cape. It's commonly eaten by grazing animals that prefer tall grasses. It grows to 1,5 metres tall and flowers from June to November.
Love grass , also known as sand love grass, is a clumping grass with medium- green foliage, which grows 30-60 cm tall and is found in all areas of South Africa.
It has a lengthy flowering season from August to February.
Thatching grass is found mainly in the north and the east of South Africa. It's often the dominant grass in areas where there is an annual rainfall of more than 600 mm. It has a long pollen season from September to February.
Kikuyu is a fine-leafed creeping grass that forms a dense turf and is used for lawns in many urban areas. It has a particularly long flowering season of six months, lasting from September to February.
Rye grass is found in the southern, eastern and northern parts of South Africa. It's often blended in lawn seed mixtures and has a pollen season from September to November.
Other trees that may cause allergic reactions include the olive, willow, poplar, cottonwood, jacaranda and the indigenous stinkwood. Birch trees are highly allergenic.
Other grasses common to South Africa which may result in hay fever are wild oats, reed, cocksfoot, nut grass (sedges), velvet, rescue, Bahia and Kentucky blue grass. Driving through farmlands where cereals such as oats, wheat and maize (forms of grass) are grown may cause allergic reactions.
Canola is increasingly grown in South Africa and can certainly cause allergy-like symptoms but it's unclear whether this is due to an allergy to the pollen or irritation of the nose. While weed pollens are a major cause of asthma in Europe and America they're not thought to be important triggers in Southern Africa. Weeds that can cause allergic reactions include Goose foot, saltwort, English plantain, sheep sorrell, tall khaki weed, scale (saltbush) and hairy wild lettuce.
(Health24, updated April 2011)
Secrets of breathing better with allergies
(This is an edited version of a story By LYNN GIDISH that originally appeared in YOU Pulse / Huisgenoot-POLS magazine, Spring 2007.)