Thanks for all the help Mark and John, now if someone could tell me what a dormant oil would be, and if a nursery would carry it, I would be eternally grateful.....

David

Reply to post by David Brunner, on November 15, 2001 at 13:27:17:

First a comment on the possible pest. I'm going entierly from memory of a problem 15 years ago or so... so this might not be complete. John mentions both petiole borer and a gall former. I think the "aesthetic only" observation applies to the variouis forms of gall... nipple, spindle, rib. I do not know if it is the very same pest but I have seen a problem, recurring but only on one hickory tree, where the emerging leaves were knocked right off the tree... 95% defoliation. It was identified by a colleague as petiole borer, based on the only other time he had encountered it... also on a single tree.

Now the curious thing is that the timing of this was either just after a somewhat late in the period "dormant" spray or at the same time as an early foliar spray or maybe a "delayed dormant" spray. And the semi-informed homeowner insisted the deoliatio was the result of the spray... phyto-toxicity.

The tree was located on a rock ledge and might indeed have ben moisture stressed.

Now, onto the "dormant oil." Historically this was an oil material that was applied in the dormant period (buds still tightly closed) a) because it was a good time to control overwintering pests before they became active and b) because the oil would damage foliage.

Now days, most "horticultural oils" are sufficiently refined - 60 or 70 second viscosity - that they do not damage most foliage and can be applied at most times of year (some species are sensitive and high heat and or humidity can make any spray phyto-toxic).

So you need to check local recommendations to see if a) horticultural oil is recommended for your pest on hickory and b) if the "dormant" period is still the best timing.

Finally, you will need equipment to adequately cover the tree.

Reply to post by David Brunner, on November 15, 2001 at 13:27:17:

Oils and soaps are used to suffocate the pest, so you would have to get the female as she is laying the eggs.

My experiance is a few years old, at the time the only foliar systemic that worked well was Orthene. Not realy good with a tall tree concidering drift issues. I understand that there are newer systemics with shorter half-lifes around now.

Then there are soil systemics such as Merit wich needs to be put in the ground rather early, and metasystox which is rather "hot".

I have not read the lables of either product lately. As with any pesticide, read the labed, for it is the law.