A weed is any plant growing in the wrong place. This is what all horticulturists are taught from the very beginning.
It includes plants like couch or kikuyu - good in the lawn, bad in the garden. A sunflower in a sorghum crop, maize in a sunflower crop or carrots in lucerne paddock.
So why did God create those weeds which are pests wherever they grow?
African love grass
My main concern on the farm is the broadleaf weeds which impact the pasture, weeds such as stinging nettles and marshmallow but there’s dozens more like various kinds of cactus (velvety tree pear, prickly pear and tiger pear), Bathurst burr, blue heliotrope, cobbler’s pegs/devil’s pitchfork, turnip weed, mother-of-millions, khaki weed and many of the different types of thistles (saffron, spear, variegated, skeleton and St Barnaby’s) then one I dislike more than most, thornapple (datura).
One weed only introduced in the past 40 or 50 years is African love grass (ALG) which is almost impossible to eliminate and can only be managed by slashing, cultivation, chemicals or fire but it returns faster than good grasses and chokes them out.
At home we have acres of this pest.
Sheep, cattle and horses are only able to eat ALG for a short period of time while fresh out of the ground. Within days the stalks appear and not only do the livestock leave it alone, it has no food value at all.
What’s worse is, the second year, love grass grows up through the middle of the plant, pushing the earlier growth outwards, thus covering pasture and preventing it from growing underneath. The third season compounds the problem and on it goes.
Control methods
Apart from this ALG, which no-one loves, most weeds can be controlled with various chemicals and there are a growing number of biological control measures being introduced, the most famous of which was the Cactoblastis moth (Cactoblastis cactorum), introduced from Argentina in 1925 and released in 1926 and which is regarded as one of the world’s most spectacular examples of biological weed control (prickly pear).
Before the release of the Cactoblastis moth, prickly pear had overtaken 60 million acres (24.3 million hectares) of land in New South Wales and Queensland, making the country unusable.
By 1933 it was estimated 80 per cent of the infested land in Queensland, and 50–60 per cent in New South Wales, had been cleared.
The results exceeded the scientists’ hopes. The moth eggs hatched out caterpillars which ate the insides out of the pear, leaving mere shells … and multiplied at a phenomenal rate.
Here at home we don’t spray the small amount of prickly pear there is, rather leaving it for the Cactoblastis to use as a home.
Did The Fall do it?
So, why did God allow these pest plants like stinging nettle or nut grass into His perfect world? Something I struggle to explain.
Was it due to The Fall?
In their native lands, many pest plants are not regarded as pests as, over time, they have been controlled by natural enemies or have been used for food, such as the pear which grows on prickly pear or for colouring such as the cochineal found in the pear.
Blackberry is another pest here in Australia yet what would we do without blackberry jam on our morning toast?
In my time, I’ve noticed most pest weeds and plants don’t grow in well-covered pasture but they grow quickly in disturbed ground such as washouts and ploughed ground.
In Europe for instance, the Flanders Poppy is considered a pest in crops but it will not grow in undisturbed soil.
Here’s my theory.
Most pest weeds grow faster than a native grass, improved pasture or a crop in disturbed ground and I believe God made it this way in order to stabilise the ground while the grass recovers and goes on to eventually choke out the weeds. For example, in a washout.
Having trialled this on several occasions in the past 20 or so years, I’ve found it has worked, even though I’ve sometimes had to spray out the hardier weeds later to allow the grass to grow further.
Would any of us thought this through? No, but our loving Heavenly Father saw what we couldn’t.