The picture above shows that the movement of Latex is from root to leaves. Carbohydrates from leaves will reach the roots through phloem to grow roots.
The following points are a few findings from experiments and experiences to prove that magnesium deficiency is the reason for “Brown bast”.
1. At the initial stage of tapping one or two rubber trees effected by brown bast. After giving a long rest dry bark forms from bottam to higher level mainly up to the union of branches.
2. After one year of tapping the DRC at tapping panel was low and the DRC over the tapping panel was high cut on bark.
3. After three years of tapping a few trees effected pink disease with a flow of high DRC at the level of union of branches. A few trees were effected by patch canker on higher part of rubber trees.
4. After the completion of ‘A’ panel and the tapping began on ‘B’ panel a portion of bark with empty milk vessels at the hight of upper level of ‘A’ panel was felt.
5. To remove the high DRC latex from the upper bark a trial of two tapping panels on ‘B’ panel both downward and upward was done at the same day and procured more yield. This trial failed to bring the DRC of upper level to lower level.
6. At the begining of brown bast a trial done to bring the high DRC latex from upper portion with an application of ethephon (stimulant) by a 2 inch width from top to tapping level also failed to do so.
7. To reduce the effects of Brown bast with the lace application of ethephon on tapping panel it was found that thick dry bark separated from stem including those with lower untaped bark.
8. By the lace application of ethephone on RRIM 600 it was felt that Brown bast occured fast.
9. A trial done in RRIM 600 with a tapping panel from left lower to right higher level, got a best result due to the flow of latex from right lower level to left upper level approximately 2 to 7 degrees.
10. On a scratch on new bark green bark was available on yielding trees. But the new bark of brown bast effected trees was without green colour on a scratch.
11. Dr.Thomas Varghees adviced to apply magnesium which is the metalic constiuent of chlorophyll to build or to maintain green bark on Rubber trees.
12. On a trial in summer rain for few trees with the application of magnesium sulphate over ash of burned leaves around trees resulted in good increase in dripping/high yield.
13. By the application of factomphos, potash and magnesium sulphate the dripping rate reduced in rainy season with more coagulating agents in latex and it was a failure.
14. The advice of a Botany teacher that magnesium will react in acidic soil by applying chemical ‘N’ (nitrogen) and the same was agreed by Dr.Thomas Varghees.
15. A trial done on a tree of Nandakumar who is a neihbour and rubber cultivator by giving rest for Brown bast effected portion and started downward tapping at the hight over 8 feet with the help of a small lader. The successful result was achieved by this way of tapping to treat brown bast.
16. Many of the plantations are the victims of dry bark on stem including untaped areas due to the defficiency of magnesium. Magnesium applied trees showed greenish stem with thin dry bark.
17. By the application of magnesium sulphate in November 2006 the result appeared in January 2007. The increased pressure by downward flow through phloem with carbohydrates and upward flow of latex in milk vessels with high DRC resulted in visible leakage of high drc latex at the level of branch union only for magnesium applied trees. Due to summer it will not result in pink disease. Productivity increased by application of magnesium sulphate.
From the above experiments it is felt that magnesium is capable to protect Rubber trees from brown bast. Magnesium defficiency occurs through droubt, acidic soil, organic peat soil, harvesting etc. Brown bast is a disease called “Necrocis” with dead tisues and by the application of magnesium with carbonate or sulphate is capable to maintain live tisues. Nuetrients water etc from soil are moving upwards to the leaves through zylem and the availability of sunshine, carbon from carbon di oxide, oxygen and hydregen from water will prepare carbo hydrates at clorophyll of green leaves. Carbo hydrates moves through phloem over cambum to grow the roots. The magnesium is available in all parts of the tree and it is known as the carrier of phosphorous. After the growth of roots balance items will move up to the lowest branches and leaves. The photosynthesis through the bark of the stem helps to store food in stem which is capable to give latex. If magnesium is defficient the leaves of lower level branches will change the colour to yellow, dry and fall down. In conclusion the movement of latex is from root to leaves and not from leaves to root. So many practical evidences are vailable to prove it.
Nandakumar with the rubber tree recovered from Brown bast.
An advance information is available that rain fall will be low in 2007. Thus the application of magnesium sulphate will increase production and will protect rubber trees from brown bast.