Topping late normally results in poor yield due to reduced leaf expansion and decreased leaf weight. Topping is generally a process of removing the budding part of the tobacco plant which will, if not removed, flower and produce seeds.
It must begin as soon as the uppermost reapable leaf is of such a size that it will not be damaged by the topping operation.
Topping will enable the plant to produce good quality and heavy-bodied darker tobacco leaf that matures more uniformly as well as contain more nicotine.
If topping is not done and the plant starts flowering, energy will move to the bud for seed production at the expense of leaf production hence removing the bloom will redirect energy to the rewarding leaf production.
Early topping schedule is also encouraged as it is important for aphid control.
Topping late normally results in poor yield due to reduced leaf expansion and decreased leaf weight.
Research has shown that the yield of tobacco is reduced by 1 percent for every day of delayed topping.
Once one has topped his/her tobacco plants, they should expect the growth of secondary stems from the base or leaf axil known as suckers that also need to be removed.
As a result, soon after topping, either by hands or through the use of mechanical tools, an appropriate suckercide or suckercide and aphicide mixture needs to be applied to the plants.
Water should be added to the suckercide and the mixture should be stirred and not be allowed to settle for too long.
The treatments in which the contact (which is not absorbed by plants and require direct contact with suckers), and systematic suckercides and aphicides (which are absorbed by plants and move inside the plant to active growth sites and inhibits additional growth of suckers) are mixed do not only save time and costs, but also ensure sucker control for up to five weeks after application.
In the application of the chemicals to the plant, caution needs to be taken to ensure that the chemicals do not splash over the top of the leaves.
Excessive residues on the cured leaf can discourage buyers of tobacco hence farmers should apply stipulated quantities.
In wet weather, it may be necessary to repeat suckercide or aphicide applications as rain can wash away the chemicals.
The chemicals control small suckers while big suckers have to be removed by hands.
Farmers are encouraged to continue checking the plant for sucker regrowth and if she/he notices green and growing suckers she/he must remove them and re-spray.
Poor sucker control frequently happen if plants are not in an upright position resulting in the chemical not coming into contact with all the sucker buds on a leaning or bent plant hence there is a need to straighten any tilting plants before applying chemicals.
During prolonged periods of high temperature and dampness, contact chemicals can cause some loss of lower leaves because of stem rot.
Uneven crop also makes it difficult to identify proper topping time hence farmers are advised to only top those crops that would be ready before they can come back and top the remainder of the crop as it matures.
A farmer can, during topping, decide the number of leaves to retain, which is usually 18, 20 or 22 depending on the tobacco seed variety as too many leaves increase labour and makes leaves compete unnecessarily for nutrients thereby making them narrow, small and light.
Whilst throwing away large leaves may seem wasteful, it is required to achieve most favourable results.
A farmer may also decide on the leaf plant positions to retain in line with market demand as there is a difference between primings, lugs and cutters, lower leaf, upper leaf and tips in terms of demand, which also affects price.
After topping, the remaining leaves will grow and more than compensate for those removed.
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