June 2012. Seedlings of Jatropha grown in a nursery in Binh Thuan province, Vietnam are “pinched” to remove the top bud before being planted in the field. The rot starts from the top down. Last year, 80% of the seedlings suffered a rot of stem (tip blight), and this year it is 25%. Pestnet members were asked to comment on what might be causing the problem. Isolations have found Botryodiplodia, but that is not thought to be the primary cause of the problem.
One member compared the condition to what happens when the tops of tomato are removed: often it results in dieback or a rot, and recommended that “pinching” should stop.
Another suggestion was that after “pinching’ in the nursery and transit to the field were providing conditions conducive to infection. Comparisons between pinched and non-pinched plants were needed before more could be said about the condition.Later, the author said that both pinched and non-[inched remaining in the nursery are fine. No problems develop.
In response the writer from Cambodia presented the following:
Concerning seedlings transport, the conditions are:
- Seedlings are close together during 3 months in the nursery (10×15 cm)
- On the day of transplantation, the seedlings are close together for an 1 hour before being moved to the field
- Transport to the field takes about one and half hour
Soft cutting (presume “pinching”) is done 21 days before transplantation, but no symptoms are seen before transplanting to the field. During transport, roots (roots only, not stem) are protected by the bags.
It was suggested to plant some in field with out pinching and some that are pinched after transplant recovery and compare. It was also suggested that as the bag is small in relation to the size of the plants you should not need to add water provided the bag is sealed.