Pests of Jatropha

[Matthew Cock]

I was looking for information on as to what insect pests and diseases attack Jatropha (either the crop J. curcas) or the weed (J. jatrophiifolia) and found very little so far. There was one abstract from India. The Australians have been working on the insects attacking the weed in the Neotropics, but have published very little on the associated insects. What else is out there?

[Ala Mena]

The symptoms occur together, as a rule and are therefore described as a complex. Whether it be one or more of the harmful causes is to be seen yet.
- new shoots are inserted into the leaf scars only to drive but is not at the leaf scars "bleeding" the plant, it always affects the upper nodes of a shoot, often the whole drive and sometimes all shoots of a plant
- diseased plants showed no inflorescences, while all the healthy plants already had several buds.
- advanced symptoms: dark spots on the branches (other green areas), showing a longitudinal section of lesions, which propagate inwards
- "red stem": “drying” of the shoot, particularly common in the basal area or of interfaces based
- increased removal of the bark, with further softening, necking with browning in the root interior, and eventually death
- according to local observations are symptoms often associated with drought stress
- according to local observations are also the roots are often affected

Thank you!

[David]

Could you confirm if all of these photos were taken at the same time? What time of year were the pictures taken, what season was it, and what was the weather like during this time?

 

Were these trees recently pruned? Picture 1A shows what appears to be sap loss from a pruning wound and the trees look they are struggling to recover from the pruning. If this was a pruning treatment, can you tell us more about the treatment applied and prevailing climatic conditions before and afterwards? The other photos look similar to bacterial and fungal attacks I have experienced caused by tree pruning at the wrong time.

[Ala Mena]

Hello David,

A lot of thanks for your answer,

Yes, you are right, the plants were pruned. It was a “standard pruning” - pruning to 65 cm height before the subsequent rainy season → September-October (Madagascar). But it was a really draw year – no rain and the temperature was about +30°C. 

Dear David, what do you think about possible pests or diseases, what could be typical in this situation for Jatropha?..

I would be grateful for any suggestions,

Thanks in advance,

Ala Mena

[David]

By the way - Im happy to have come across this and be able to share our experiences with pest and diseases of Jatropha.

Thank you everyone for their contributions.

 

Its clear that different regions are affected by different pests. in Se Asia, I have experienced large-scale pest problems with broad mite, mealybug, pempelia morosalis, scales, leaf minor. Other pests, whilst seen on the plantation, have had no commercial impact on production. I also experienced problems with fungus and bacterial attacks. Most of these have been due to avoidable errors in site and soil management.

 

Thanks again all,
Dave

[David]

Because Jatropha holds its moisture in the outer cells of the tree, it can be strongly affected by pruning at the wrong time.. I never prune during dry season or during extremely hot weather. My hard prune comes a few weeks before first rains are expected as there is normally enough water and nutrients to get through to the rains. When rains have been late, Ive had problems, when Ive pruned in dry season or very hot weather, Ive also had problems.

Seems the stress from the moisture loss lowers the trees immune function making it susceptible to fungal or bacterial attacks. Yours could be a case of either and you should get a lab analysis to be sure.

 

Normally I can tell if I am going to have a problem after pruning if I see excessive sap coming from the prune afterwards. If the wound heals up and there is no bleeding of sap, it is ok. But if there are big sap stains, I know to expect problems.

 

When my trees have been affected in this way, the problem got worse very rapidly, so I didnt wait for lab analysis.. I just treated with a broad spectrum anti fungal, followed 2 days later by broad spectrum anti-bacterial. Stopped the problem and the trees came back eventually.

 

Sometimes the damage done will also affect your ability to get your desired branching, so after full recovery you may have to prune again to get your desired branching, if you are still in season.