Personal settings is a facility available to Pro
and Pro Plus
subscribers. This facility enables you to save and later reuse information from your own fields, your own customers or your imagined scenarios (combinations of crops, herbicides, weeds etc.). A selected personal setting will persist, also when you switch between tools. Press the link, select Edit to Add, Rename or Delete your Personal settings. For subscribers to Basic
, only 1 Personal setting will be available and cannot be edited.
Crop, Undersown and Season
The competing ability of crops (including possible undersown crops) against weeds influences the efficacy targets in IPMwise, and the options for control (herbicides and mechanical control) available.
Season separates Autumn from Spring/summer and is defined by calendar dates. Season ensures a correct handeling of crop growth stages, which may occur both in the autumn and in the spring.
Crop growth stageExpected yield
The crop growth stage determines available options for control (herbicides and mechanical control). To avoid confusion, only growth stages where control measures are available, are shown. Many weeds will often only be listed in early growth stages where many options for control are available (sufficiently effective). In many newer registrations of herbicides (labels), the allowed max. doses increase with increasing crop growth stages, while the susceptibility of weeds drop accordingly, due to the larger growth stages also of weeds.
Information on expected yield is only requested in cereal crops. An expected, relatively low level will affect the expected competition with weeds, which is compensated by slight increases in effiacy targets of IPMwise. In Danish cereals low yield levels
are defined like this:
- spring cereals: < 50 hkg/ha
- winter cereals: < 60 hkg/ha
Water stress (weeds)
Drought stress implies that the expected efficacy of herbicides will be reduced drastically. However, drought stress, is only rarely seen in Denmark, and usually not on small weed plants at all. As long as weed leaves bristle as normal, water stress (affecting herbicide efficacy) is not expected. Drought stress may be detected from visual symptoms on weed plants, e.g. characteristic hanging or curling leaves. In case of water stress, herbicide dose rates often need to be indreased by 50%-500% to maintain efficacy levels. In such cases, maximum dose rates are likely to be exceeded, why a reasonable recommendation will be to wait for rain or a shower.
Minimum and maximum temperatures
The temperature before, during and after herbicide application may influence efficacy, where the temperture close to the time of application has the dominating influence. For most herbicides, increasing temperatures will lead to increased efficacy (as long as no severe drought stress is present). Min- and max. temperatures refer to the day of herbicide application. Even in extreme temperatures, adjustments of herbicide doses rates will often only be in the range +/-10-15%.
In IPMwise, optimization (minimization) is used to find the lowest: cost of control, treatment frequency index (TFI) and environmental load index (E-load), which was introduced in Denmark in 2014.
In some crops, some weed species can be almost ignored, while other weed species need effective control even when present in ratherlow densities. Furthermore, the susceptibility of weeds to herbicides differ strongly between species, as some herbicides have sufficient effect on some weeds in dose rates down to 5% of registered dose rates, while other species cannot be controlled sufficiently even by full dose rates. Therefore, correct identification of weeds is crucial in most cropping systems, both to ensure proper control and to minimize the use of control measures. When weed biotypes, resistant to specific herbicides (MOA), are reported, efficacy of herbicides with those MOA will be set close to cero and efficacy targets will be set to maximum values (resulting in very effective control by alternative MOAs). Resistant biotypes are marked with the MOA group in the so-called H-RAC system, which is also shown in the tool Herbicide mode-of-action. In Denmark, resistance have been found in 2 H-RAC groups so far: A and B. Resistant biotypes have been named by use of the botanical weed name plus -r (for resistant), e.g. B-r (resistant against herbicide MOA B.
The growth stage of weeds affects the efficacy of herbicides. In general, small seeded weeds are more susceptible than bigger plants, while perennial weed species (germinating from roots) are often more susceptible (to achieve long term control), when they have developed enough leaves to ensure also considerable translocation to root system, i.e. when minimum 3-4 leaves have been developed. Field inspections shall be made for seeded weeds, as soon as species can be determined, i.e. when plants have about 1-2 true leaves.
The density of weeds influences target effiacy levels.
Effect goal (or target efficacy) denotes the level of desired weed control in percent. The target efficacy can be determined by IPMwise or you may decide the target efficacy level yourself. The 1st item in the list is named, IPM, where the level of control is decided by IPMwise and usually sufficient for a normal Danish field to ensure yield potentials and to avoid weed propagation (demonstrated in many years of applied research). In some cases, however, increased efficacy targets may be justified, e.g. when the next crop shall be used for seed production, where specific requirements for low content of seeds for particular weeds must be met, why effective sanitation in the previous crop may be justified. In other cases, where control options are sparse, lowering of effiacy targets may be considered to enable at least some recommendations (including maybe also unsatisfactory control).
The IPM option in the list determines efficacy targets, while integrating the following aspects:
- competition from the crop
- potential losses from weeds in actual crop and following crops (yield and propagation)
- weed density
When you add another weed species or make a calculation, the tagged weed will be deleted/forgotten from the list.
Show prevention of resistance
Herbicides' modes-of-action is also referred to as MOA. In Denmark, cases of herbicide resistance have until now been reported mainly for 2 MOA groups:
- Group ACCase, which in the H-RAC classification is referred to as Group A. ACCase refers to the biochemical MOA, which is blocked by the herbicide. This Group is also referred to ast the fop/dim Group, as most of the the herbicide MOA names in this group end like this.
- Group ALS, which in H-RAC classification is referred to as Group B. ALS is the name of an enzyme, which is blocked by herbicides from Group B. Sometimes, ALS-herbicides are also referred to as sulfonyl-urea herbicides, however, ALS also includes other molecules.
There is widespread consensus to the perception that herbicide resistance may occur as a result in particular of the following 2 conditions:
- natural mutations i genomes of weed species, where resistance will occur spontaneously from time to time
- unilateral and repeated use of MOA, against which resistance has already been developed. Consequently, propagation of reistant plants (biotypes) will be promoteded, according to the spread biology of the actual species
However, only sparse knowledge is available on how, herbicide resistance is most efficiently avoided/delayed, and ressources are not available for 5-10 year studies to quantify risk of various strategies to avoid/delay additional development of resistance.
In IPMwise, strategies to prevent/delay herbicide resistance is therefore designed by use of common sense, and an initial general strategy is to use risky MOA (MOAs where resistance have already been reported in more cases) in max. every 2nd generation of weeds. In addition, current results from monitoring by the Nordic NORBARAG group, will be interpreted to decide, whether decision algorithms should be adjusted furtherly.
You may determine, however, how strict this general rule shall be applied: 1) by restricting measures to prevent/delay addtional resistance to fields, which include weed species, which NORDBARAG consider threatned (according to incident reports) 2) by systematic use of herbicide mixtures of risky and non-risky MOA (pre-formulations, tank-mixtures). This strategy must, however, be considered as relatively risky, as fields may be found, where only risky MOAs will ensure the effiacy one some weeds, and in this way promote propagation of resistant plants.
IPMwise generally recommends to shift as often as possible between MOAs. However, as a result of the relative sparse level of documentation, IPMwise let users determine, how restrictive rules that shall be applied. In general, unilateral use of a risky MOA may be acceptable for relative short period of time (e.g. in a special crop grown on few hectares), while unilateral use may be considered harzardous in crops grown on many hectares and more frequently.
In the list of recommendations for treatments, information is included on species considered subject to particular risk for development of herbicide resistance.
My (own) herbicides
If you choose to restrict recommendations for control to your own list of herbicides and prices (Pro Plus subscription), optimization of control options will be made only by use of these (when efficacy targets can be met).
Suggestions for treatment
In the top of output, the reported conditions for calculation, efficacy targets according to IPM or your own targets are presented. Suggestions for control may include legally available herbicides (single products, adjuvants, tank-mixtures) and mechanical control, which can provide the requested levels of target efficacy. By unfolding the list of suggestions, more detail information will be shown, e.g. special legal restrictions, alternative (generic) herbicide and adjuvant products, expected efficacy on a weed species level. Risky MOA will be marked with a *.