The effectiveness of herbicides is definitely diminishing and have been for a while.
This season for, a number of reasons, exposed some big problems. We over use herbicides.
A classic example is when we spray and a few weeks later we notice the herbicide has had little effect.
The reaction is to go back over it again therefore just piling on even more chemical (one of the reasons why we are adding to chemical resistance). This reaction is becoming commonplace.
As a winegrowing /horticultural community we need to become mindful of how we manage herbicides. The ideal conditions for applying herbicides are when plants are actively growing, conditions are moist (high humidity), cool temperatures and low wind conditions.
The least favourable conditions are when plants are hardened, water stressed, dusty (dust plays a big part in reducing efficacy), high incidence of bare soil, high ambient temperatures and higher wind conditions.
The difficulty is to find the best time to spray between the ideal and not so ideal to achieve the best results-this can be often tricky.
Herbicide resistance is the growing problem. Some common herbicides will be deregistered within the next 10-15 years. Now is the time to look at alternatives.
The obvious technique is mechanical under vine weed management. It has a number of benefits. We can enliven our soils by massively reducing chemical load and help reduce resistance to chemicals if and when we need to use them.
The technologies have come a long way and are evolving rapidly with mechanical under vine weeding equipment.
Now is the time to plan your vineyard or horticultural enterprise to enable the introduction of new and evolving weed manage techniques that reduce reliance on soil chemical loading.