Detailed protocol: Preparation and application of pesticides

How much pesticide per plot?

We use a Karate Zeon suspension which contains 100g/l of the active ingredient Lambda-Cyhalothrin, a Score suspension which contains 250 g/l Difenoconazol, and an Ortiva suspension which contains 250 g/l Azoxystrobin. The molluscicide (slug pellets) use the active ingredient ferric phosphate, with a concentration of 1.25%. It might be that in your country these numbers are different, and that the products you can buy are more or less diluted. In this case you might adjust our calculations a bit, so please check this before! If you don’t know how to do that, don’t hesitate to ask!

As none of the compounds are usually used in grasslands, we will use recommended concentration of the pesticides for crops that are most closely related to a grassland (cereals). We use the following recommended concentrations (based on the suspensions of our products, described above):

FungicideOrtiva: 1L/ha = 0.1 mL / m²
Score: 0.4 L / ha = 0.04 mL / m²
InsecticideKarate Zeon: 75 mL / ha = 0.0075 mL / m²
Molluscicidee.g. Limax Ferro: 5g / m²

The application of the molluscicide is the easiest – simply spread 125 g of slug pellets evenly over each M+ plot. For the insecticide and the fungicide, based on the numbers above we can calculate how much of each product needs to be sprayed per 25m2 plot (simply x 25), and we can also work out the amount of water to dilute it and to make the application feasible.

It is important that we only apply a thin layer/film of liquid on the plant (Syngenta recommends to dilute the pesticides in only 1L per 25m2 plot). It is therefore recommendable to use a very fine sprayer. If we apply too much liquid, the active compound drops to the ground and does not stay on the leaves. However, depending on your sprayer, 1L for a whole 25m2 plot might be too little, and you might need more liquid. In this case you can dilute it in 2l water, to make the application easier. We recommend that you figure out the amount of liquid that is necessary for your sprayer to spray an area of 25m2 beforehand. Very handy are the sprayers that you can wear on your back, and you can pump to keep the pressure constant while spraying (see pictures A), but also the cheaper hand-sprayers will work well (e.g. picture B).

Fig. 1: A)Example of a sprayer that you can wear on your back, and B) a hand sprayer

How to prepare the pesticides?

Two plots per block (the -I+M+F and -I-M+F treatment combinations) receive insecticide only and no fungicide, two plots per block receive fungicide only (+I+M-F and +I-M-F), 2 plots per block receive insecticide and fungicide together (-I+M-F and -I-M-F), and two plots receive water only (+I+M+F and +I-M+F). That means, that we have 6 plots for each pesticide application. You can either mix the pesticide-water mixture for each plot (pesticide + 1L water), each block (2 x pesticide + 2L water) or for all six plots together (6 x pesticide + 6L water). The way you do it depends on the size of your sprayer and whether you are able to see how much you have sprayed on one plot already. If your sprayer has a constant spraying pressure, you can for example measure the time of spraying until 1L of liquid (or the amount of liquid that works well for your sprayer) has been sprayed, and then spend exactly this time spraying on each plot.

Prepare a concentrated solution in the lab

Since the used quantities of the pesticides are very small and are difficult to measure in the field without a proper pipette, we recommend that you prepare a concentrated solution (the amount of pesticide needed plus a bit of water) in the lab. You can use small vials, e.g. 50 mL falcon tubes which you will then bring to the field and which you will add to your sprayer and dilute in more water (Fig 2). The amount of vials you need to prepare depends on whether you fill your sprayer with the pesticide-water mixture for each plot, block or for all plots together:

For example, if you decide to always prepare the pesticides for each plot, you also need to prepare a concentrated solution for each plot (see table above, e.g. for the insecticide only treatment a tube would contain 0.1875mL of Karate Zeon and 50 mL of water). In this case you need six of those vials for each pesticide treatment (18 in total), which you bring to the field. In the field, you can then simply add the content of one vial to your sprayer, and fill up with water until you reach 1L, and you repeat this for each plot.

Fig. 2: Prepare the concentrated solution in the lab and bring to the field. In the field you simply add the concentrated solution to your sprayer and fill up with the required amount of water (see table).  

How to spray?

Familiarize yourself with the manufacturer’s safety and application instructions before using the pesticides. Also make sure you have emergency plans in place, e.g. what you would do in the event of a medical emergency (eye contact with pesticides, inhalation/ingestion, etc.) or if you spill undiluted pesticides on the ground. When handling pesticides, always wear chemical-resistant gloves, rubber boots, suitable disposable protective suits and a full face mask to protect against particles and gases (the standards of protective equipment should meet the requirements described in the manufacturer’s safety data sheets). Depending on the region of the world, availability and standards may vary. Here you will find a non-exhaustive list of protective equipment that we use in Switzerland:

Glovese. g. ALPHATEC®SOLVEX® 37-675
Rubber bootse. g. Safety boots, wellingtons, Portwest WORK, Safety Food FW 84
Overalle. g. ALPHATEC® 2000 STANDARD BOUND – MODEL 111
Full face maske. g. Dräger X-plore® 5500 with Dräger X-plore bayonet combination filter A2B2 P3 R D 6738776
Emergency equipmentEye shower, shovel and container to take up spilled pesticides, etc.

If you only have one spray bottle, start by spraying the plots that are not to receive fungicide and/or insecticide (as a control) with water. Then apply one pesticide at a time. Cover the entire plot with a thin layer of the pesticide (or water for the control) until all the leaves are moistened. Spray the pesticide low on the vegetation to avoid spillage, especially if it is a bit windy. Pesticide residues in the spray bottle can be safely disposed of by spraying them on the vegetation in the same way, e.g. on a designated “leftover plot” at the study site where they can be safely broken down. After spraying, do not work on the plots for at least 48 hours!

Fig. 3: Example of protective equipment used for spraying.

When to spray?

You should spray fungicide and insecticide and apply the molluscicide at the beginning of the growing season, and then every 4-6 weeks until the end of the growing season. The number of applications will be larger in regions with a very long growing season, but this is appropriate given that the consumers are active for longer and that we want to ensure that they are effectively reduced in abundance. However, do check the local regulations in your area and make sure you do not apply pesticides more than is allowed. Record the dates of the application. Choose the day and hours when you can spray the pesticides based on the weather forecast that day. It should be dry, sunny and not windy. Even a weak wind can result in spill-over to neighbouring plots! In several countries there are special online tools for farmers to know when to spray (in Switzerland for example Syngenta offers a tool called Phytometeo), maybe there is something similar in your region?

Try to only prepare as much pesticide-water solution than you also need to spray and avoid leftovers. If you have pesticide leftovers, never add them to rivers or water bodies, as they can harm the environment.

You will need:

  • the pesticides (Karate Zeon, Ortiva and Score or other products with the same active substance)
  • gloves and protective clothes, masks
  • little tubes of ca. 50 ml (number depends on the way you spray, see table) in which you mix a concentrated pesticide solution in the lab before going to the field
  • water for mixing the pesticide solution and for the control treatments
  • one or two spraying bottles (one for the pesticide application, one for the controls)