Perhaps we could include: "It is suggested that the manufacturer discuss the protocol of the evaluation with the IIC before starting trials". As the end product is used for human consumption, residue tests must be carried out according to the requirements of the Registrar (Act 36/1947) (Article 6). Details must be provided on the type of equipment used for the application of the PPA.
This is a requirement of the tobacco industry and the reason why should be self-explanatory.
Rhizoctonia leafspot, shot hole [Thanatephorus cucumeris (Rhizoctonia solani)
Percentage healthy plants are to be determined three weekly up to at least 15 wk after transplanting in an infested field. Can these trials with this pathogen only be done in seed tray trials and will this be acceptable for registration purposes. Dis tog seker voor die hand liggend dat daar nie saailaaiproewe gedoen gaan word as die siekte slegs op volwasse tabak in die land voorkom nie.
We suggest that everything that is said about individual diseases and pests be deleted from the document.
INSECTICIDES AND MITICIDES
LOCALITY
- Boll worm (Helicoverpa armigera)
- Aphids (Myzus spp.)
- Thrips (Thrips tabaci)
- Mites
- White fly
Suggest: "Where experiments can be carried out, they should be on different soil types and under conditions that vary as much as possible". The attack potential of the insect/mite in question should be sufficient in the area where the experiment is to be carried out. When evaluating pheromone and other monitor systems, such trials should be discussed with the appropriate advisor in advance.
The minimum number of replicates required for statistical analysis should be determined based on the number of treatments.
NEMATICIDES
TRIAL LAY-OUT
TRIAL LAY-OUT POINT 2
Nematode counts from representative soil samples must be carried out by a qualified nematologist immediately before the experiment begins. The questions that should be asked are what are our goals when we do nematode counts and are we achieving them. At the beginning of the growing season of annual crops, plant parasitic nematodes are often not in an active stage or occur below the root zone where soil samples are taken, or occur only concentrated in small areas of a field.
Detailed nematode counts (by plot) in soil at this stage (or at later stages for that matter) usually result in totally useless and confusing data, due to very low soil counts at the beginning (before the susceptible crop is planted) and wide variation in soil counts. Even square root counts often do not give a clear picture of the actual situation due to great variation. Under controlled conditions, where artificial inoculations are done, or where a susceptible crop, such as beans, is planted to activate and build up nematode populations before a nematode trial begins, it may be worthwhile conducting nematode counts.
However, field trials (for registration purposes) are not performed under ideal conditions and therefore the current emphasis on nematode counts should be reconsidered, especially given the high costs associated with counts. Ultimately, the higher yield and the quality of the crop are the most important parameters. Farmers are not satisfied with a lower nematode count after applying a nematicide, they are only satisfied with a higher crop yield and/or quality.
It's been a long time since we considered the high cost involved in counting nematodes and wondered: Wouldn't our end goal be equally well served by replacing the number of nematodes with other appropriate parameters. The number of nematodes should be determined at the end of the previous crop when they are present in the root zone.
TRIAL LAY-OUT POINT 3.2
Each plot should preferably consist of 4 rows, where the two middle rows (∀20 m2) function as data rows.
FIELD TRIALS POINT 5.1 AND 5.2
Control can also be achieved by disorienting nematodes, damaging the cuticle, strengthening natural enemies, increasing plant growth and resistance, etc. The use of other parameters to determine the presence of nematodes, such as temporary workers also count. Or by determining the presence and number of nematodes only with one nematode root count (after planting) in control plots.
Or do only one nematode root count in all plots, for example six or twelve weeks after planting. Nematodes have a devastating effect on tobacco and care must be taken to control the infestation. There are other ecto-parasites such as the stubby root and stunt nematode that also cause problems in tobacco and soil counts are necessary for that.
Most companies do their evaluations on the root knot nematode only, but then they have to list it on their label. It is true that certain nematicides only disorient the nematodes, but hungry nematodes die quickly and then you do not count them. With a higher yield the farmer will be satisfied, yes, but does your label say a higher yield or effectiveness as a nematicide and what happens to the next crop if the nematodes are not controlled?
SEED BED TRIALS POINT 5.1 AND 5.2
There is a trend developing within research institutions (outside and within the ARC) for nematode counts to be considered less and less important in nematicide efficacy trials. The same protocol as described above should be used for all biological control agents, but consultation with advisors is of utmost importance. When a biological control organism is introduced into the soil, soil samples must be analyzed six weeks after the introduction to indicate the presence of the specific organism.
HERBICIDES
POINT 1
POINT 3
POINT 4
POINT 4
When treating after emergence, the size of the weed, its biomass or the percentage of ground cover with an individual type of weed must be recorded before applying the herbicide treatment. After application, the site should be visited regularly and the percentage of weeds killed or stunted and the spectrum of weeds suppressed recorded. There should be a small control area adjacent to each plot that can be used to assess weed control.
Perhaps "A minimum of two non-data plants should be planted at both ends of each data row to even out the growing conditions of the data plants in the row.". 34;The minimum number of replicates required for statistical analysis should be determined by the number of treatments". The most commonly used PPA with a comparable control or effect spectrum should be included as a standard of comparison.
Sucker control should be assessed by counting the total number of suckers per plant on 10 data plants per plot at intervals and 6 weeks after PPA application. Shoot dry weight per plant per replicate should be determined by drying and weighing all shoots per replicate. Why it is necessary to determine the dry weight of mammals and how to dry them.
Phytotoxicity studies should be carried out on different cultivars of the main cultivar types grown in South Africa. The phytotoxicity of registered herbicides for new cultivars will be determined by the breeder before they are put into commercial production.
PHYTOTOXITY, POINT 2
It is more accurate to work with dry mass, because the humidity of fresh material can change. It is imperative that the experimental plots are weed-free throughout the experimental period.
PHYTOTOXITY, POINT 3
Treatments must include at least the expected application rate for registration and double the amount as well as an untreated (hand weed) control. In phytotoxicity tests, the plots must be kept weed-free so that the weeds do not affect the growth of the crop. In effectiveness trials, you determine which weeds at which stage of the herbicide treatment.
Any visual signs of phytotoxicity should be assessed at regular intervals throughout the period of active growth. The effect on yield, changes in growth rate, plant height and/or dry biomass produced during the period of active growth should be recorded. Plant recovery from initial phytotoxic effects should also be recorded and described.
PHYTOTXITY POINT 5
PHYTOTOXITY POINT 6
PHYTOTOXICITY
EVALUATION, POINT 2
By "vigor index" is meant the visual condition of the treated plant in relation to that of the untreated control plants. An example of a growth index could be a 10 point scale where the control plant has a value of 5.
RESIDUE ANALYSES
POINT 5
Green samples (to be frozen) as well as flue-curing/air-curing/sun-curing leaf samples should be taken. Take representative green leaf samples (∀1 kg) from plots of all rates approximately 14-, 16-, and 18 weeks after transplanting, depending on tobacco leaf maturation, and store in a freezer immediately after collection until ready for analysis. It is clear that the cost factor has not been taken into account when writing this protocol, for example in the case of a generic product.
Harvest maturing tobacco leaves (∀ 10 kg) for flue-curing from plots of all rates approximately 14, 16, and 18 weeks after transplanting. What if no residue levels can be detected before harvest on green samples, or on the first sampling date, or in the cured product. Of course, only the sample whose residues can most likely be detected should be analyzed first (probably the cured sample when the residues are concentrated).
The cultivar will not determine whether the finished product will be smoke or air dried. What would be the use of smoke drying the cultivar and testing for residues if the cultivar is only grown for air drying. Shouldn't it be specified that, for example, two smoke-dried cultivars and one air-dried variety should be used in the residue trials.
The same guidelines as for plant-sprayed chemicals should be used, but plots should be duplicated with multiple border species to avoid cross-contamination. Take representative samples of green leaves (∀ 1 kg) from all-dose plots approximately 14, 16 and 18 weeks after transplanting and store in the freezer immediately after harvest until analysis can be performed.
POINT 7.3.1
Residue data should be collected according to the "Agricultural Remedies Residue Trial Data Requirements Document" of August 1998 (Registrar
The Coresta Chemical Residue Committee standards for maximum permissible residues in tobacco should be used as guideline
Green samples (to be frozen) as well as samples of leaves, which have been through the flue-curing, air-curing or sun-curing process, depending
TAINT TESTS
POINT 1 AND 2
Plots should be large enough to provide at least 5 kg of dried tobacco for each treatment (approximately 15 data rows and two border rows of 50 m, depending on shed size).
