“A weapon you held and didn’t know how to use belonged to your enemy.”
This saying by Sir Terry Pratchett also rings true when it comes to protecting your crops against pests, ensuring maximum yields and minimal loss.
Researchers conduct continuous and extensive research and trials on stinkbugs and stinkbug complexes.
At the same time, numerous actives have been registered and used successfully over decades. Why do we still see the devastating effect of these bugs on our pack-out percentages?
Several factors could cause pests to continue devastating crops. However, by understanding the situation and by using the best weapons and tools, we can implement control strategies.
Scouting
It is impossible to change what you are unaware of, so scouting remains the foundation for protecting crops effectively against pests and disease.
Simply taking the lazy approach and following a general spray programme every season can be expensive and unexpected pests and diseases can go unnoticed and untreated. In addition, the repeated use of pesticides with similar modes of action can result in serious resistance challenges.
Pyrethroids might be a very economical option. Unfortunately, this active ingredient does not affect two-spotted stinkbugs in most of the northern and eastern regions of South Africa due to resistance. Identify the species during scouting to select the correct product.
Integrated Pest Management (IPM)
A good IPM approach helps prevent resistance and includes a combination of biological, mechanical and chemical control measures to reduce stink bug populations.
- Beauveria bassiana is a fungal contact insecticide and an excellent biological option as part of your IPM
- Keep host weeds and grasses under control by slashing and removing larger plants. Bugweed and castor oil plants are good hosts for stinkbugs.
- Alternating insecticides containing active ingredients from different chemical groups will reduce the risk of resistance against certain active ingredients.
The table (left) includes the most used active ingredients, the groups they belong to and their mode of action.
Several factors can affect the effectiveness of insecticides
- Spray volumes must be sufficient to ensure effective control. For stinkbugs, a medium- to full-cover spray is recommended depending on the product used. Read the product labels carefully for Under- or overdosage can seriously compromise the optimal performance of the product, resulting in ineffective control or resistance build-up. Ensure that spray equipment is well maintained and calibrated.
- Ensure good coverage by using quality spray nozzles at the recommended Use non-ionic adjuvants with spreading and penetrating properties with insecticides.
- The time of day when applying insecticides against stinkbugs is Adults migrate out of the orchards during the day when it is hot. Spray very early in the morning.
- Water quality is one of the most important factors in any spray mix. Most insecticides work optimally at a lower pH (around 5). At this pH, the products are stable and take longer to break down due to climatic factors. The active ingredients are thus available for longer to do their job. Consult the product labels for more information regarding this. Organic matter in spray water can bind with active ingredient molecules, rendering them inactive. It can result in unsatisfactory insect control.
- Weather conditions have an immense influence on stinkbug population numbers. Late-season rains can result in out-of-season hatching of eggs. Therefore weekly scouting is important to detect untimely outbreaks.
In combination with the tools and measures, an arsenal of well-tested, trusted chemical products, and common sense, we can control stinkbugs effectively. When we stop paying attention to the detail of all the different aspects of pest control, problems will start creeping in. Visit www.villacrop.co.za for more information.
