Problems, Planning and Objections in Weed Research
In planning, weed control research the various weed problems and their magnitude needs to be denotified. Problem should be handled as per priority basis. The worst weeds of cereals like Lavala should be controlled immediately. The scope and study of weed control should be clearly defined to avoid confusions and ambuiquity lateion
Objectives of Conducting a Weeds Control Trial:
1. To determine the herbicidal activity of a new unestablished compound on a particular weed or crop specied.
2. To determine the optimum rate, time and method of application of a herbicide a specific weed species flora in a crop.
3. To study the harmful or beneficial impacts of herbicide on a weed control practice on the yield and quality of particular crop in a mix or rotation.
4. To study the persistence activity and residual problem of any of a herbicide.
5. To determine the effect of a herbicide in different formulations.
6. To improve the activity of a herbicide in combination with adjuvants and other herbicides.
7. To study the changes on weed flora due to continuous use of a herbicide or weed control
8. To determine the suitability of the herbicide for a weed control in a particular crop situation.
9. To determine the duration of weed competition and the time of weeding of weed control in crop.
The successes of achieving the set objectives depend upon a number of factors:
1) Environmental factors.
2) Agronomic factor.
3) Application of treatments.
4) Plant morphology and growth.
5) Composition of tolerant stress to a susceptible weed.
6) Composition of tolerant stress to a susceptible weed.
7) Method of evaluation of plant response.
8) Data collection etc.
Types of Field Experiments:
Most of weed control experiments are testing and evaluation of herbicides which are conducted in the form of multi stage trials.
1. Screening Trials:
Primary screening of herbicides and second screening of herbicides.
2. Advanced Trials:
Once secondary screening is completed, the most promising herbicides or treatment are included in advanced trails with objective like yield, herbicide residue weed shifts, cost benefits, formulation, spray volume, regional studies, cultivars etc.
i) Yield Trials to Determine:
(a) Direct effect of herbicides.
(b) Indirect effect of herbicides. These are carried out for economic evaluation of herbicides
ii) Residue Trials:
These trails are conducted in field or green houses which are useful to determine the duration of herbicides activity and effect of the following crops in rotation and weed species infesting latter.
iii) Weed Shift:
These studies can include investigation of new or established herbicide or even a recommended practices.
iv) Herbicide Formulations:
Herbicides are available in different formulations and they can be compared at equivalent rates on the basis of active ingredients.
v) Spray Volume:
Optimum spray volume varies with the herbicide, species of weed infestation. Generally the foliage applied contract herbicides require greater volumes than the translocated herbicides.
vi) Regional Trials:
Regional trials are followed with the objective of screening up the performances of a herbicide or a treatment under diverse condition (agro climatic), soil type and cropping practices.
Crop cultivars differ in their tolerance to herbicides.
viii) Demonstration Trial:
To display the performance of selected herbicide.
ix) Special Trial:
Weed competition on study the competitiveness of weed spp. These are essential for recommendations of new herbicides.
x) Application Techniques:
Weed research is also conducted to standardize herbicides application technique.
a. Optimum spray delivery.
b. Proper sprays nozzles.
c. Optimum sprays volumes.
d. Proper herbicides application.
xi) Other Studies:
Special studies are required to determine the interaction of herbicides of weed control practices with soil fertility and nutrient levels, plant population, row spacing, soil moisture and condition crop varieties, insect and disease of occurrence.