STINK­ING MAYWEED

NZ Lifestyle Block - - A Country Life -

WHEN IT COMES to train­ing staff, farm­ers and ju­nior agron­o­mists, I re­ally love to chal­lenge and stretch peo­ple. I guess it’s be­cause I come from a fam­ily of teach­ers (mum, dad and both sis­ters).

I have fond mem­o­ries of my dad, a sci­ence teacher extraordinaire, quizzing me and my sis­ters on all things sci­ence, with the ques­tions start­ing easy and get­ting pro­gres­sively harder.

I fol­low the same prin­ci­ples when I’m teach­ing peo­ple weed ID. We start easy (a fa­then here, a shep­herd’s purse there), and then get pro­gres­sively harder (like say the may­weeds or chamomiles, the names are in­ter­change­able). There are three may­weeds and when veg­e­ta­tive they all look the same but there are some sub­tle tricks to dif­fer­en­ti­ate them.

So be­gins your lessons on the may­weeds. Stink­ing mayweed ( An­themis co­tula) is a com­mon an­nual weed of open pas­tures, waste ar­eas, crops and road­sides all across New Zealand. It’s orig­i­nally na­tive to Europe and North Africa but has suc­cess­fully mi­grated to North Amer­ica, South­ern Africa, Aus­tralia and New Zealand.

As you can see, it is a mem­ber of the Aster­aceae or ‘daisy’ fam­ily and that’s ex­actly what it looks like when it’s flow­er­ing, but there’s one other dis­tinc­tive fea­ture. It stinks!

This is a very strong, very un­pleas­ant odour which is so strong and so un­pleas­ant that an­i­mals won’t even eat the grass around it, let alone the plant it­self, which means it’s free to in­vade your pas­ture at its leisure.

While it does smell aw­ful, it’s ac­tu­ally not toxic un­less you are a cat, dog, horse or guinea pig, but you want to steer clear as it’s pretty nasty if you touch it (or eat it, which I don’t rec­om­mend). Symp­toms can in­clude der­mati­tis, vom­it­ing, di­ar­rhoea, anorexia, and other al­ler­gic re­ac­tions*.

It can be tricky to dif­fer­en­ti­ate stink­ing mayweed from the other may­weeds as they look very sim­i­lar when veg­e­ta­tive. It ger­mi­nates in the spring, usu­ally in ar­eas where there is bare soil such as waste­lands and open pugged pas­tures, and pro­duces very slight, feath­ery, dark green leaves that emerge di­rectly from the stem. It can reach a height of around 30-60cm be­fore it be­gins flow­er­ing over the De­cem­ber to March pe­riod. The flow­ers re­sem­ble the clas­sic daisy flower – 2-3 cm in di­am­e­ter with a bright yel­low cen­tre sur­rounded by white petals.

One easy way to iden­tify it is to crush some leaves and have a sniff, which will also help you fig­ure out what is: - if it stinks, it’s stink­ing mayweed; - if there’s no smell you have scent­less chamomile (the se­cond mayweed);

- if it smells like pineap­ple you have ray­less chamomile (the third mayweed).

How to con­trol it

Con­trol­ling stink­ing mayweed can be re­ally easy or re­ally hard de­pend­ing on the con­di­tions. If your pas­ture or crop is com­pet­i­tive it will out­com­pete stink­ing mayweed which needs a bit of time to get go­ing so good grass and clover will smother it out.

If it does get a toe­hold but you spot it when it’s about 2-3cm across, a spray with Re­side or Head­start will con­trol it (keep the rates up for best con­trol).

If it’s big­ger than that, you need the big guns like 2,4D or Ver­sa­till which will con­trol plants right up to flow­er­ing but they will knock your clover so try to get to them early. ■

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