How late to experience drought relief?

[wysiwyg]

We are currently in what I would call a long term drought. According to our back yard rain gage we were about 3.25 inches (10%) below normal in 2002 and 9.25 inches (40%) below normal so far this year. We are doing slightly better than Milwaukee, which is almost 11 inches below normal for the year. But from what I understand many surrounding communities have seen much more rain so this drought has thus far pretty much been ignored by the local media and even the NWS.

So far we have only lost one established Scotch Pine (good riddence), everything else "appears" to be ok. The poplars have lost about 75% of their leaves, the maples about 10-15%, oaks and hickories none. Our soil can be described as generally sandy gravel with 6 inches to 2 feet of topsoil that's currently as hard as rock. We have a deep well that has already gone dry twice in 20 years so watering is out of the question for anything but recent transplants, which have gotten good soakings once a week for the past couple months.

The last time it was this bad was in 1988, which had both drought and heat. We've so far avoided the heat, but the rainfall I think is actually less, so I'm not sure if this can be considered worse than 1988 when we lost a lot of trees, most of which actually died over the winter or the next spring.

Anyways, what I'm wondering is at what point in the year would a beneficial "drought busting" rain be too late to help our established trees? In other words, how late in the season do trees suck up water to be used in spring growth? I've always assumed that when the leaves come off all trees go dormant, but I'm hoping this is wrong as there is no sign of meaningful rain in the forecast.

 

[John Paul Sanborn]

It depends on the species, I've seen a number of birch loosing branches from borer that had been fighting it off.

DED is raging in the area, seeing a lot of ash yellows too.

A number of customers with soil that rarely dries out have wide cracks in the clay, trees having limbs competely defoliated.

If it is just a drought responce, I think we will not see many trees loose actual branches, it is the plants with a secondary stress that get way out of hand that will be causing the long term problems.

Any rain we get will have to be a slow drizzle, or it will mostly run off the hard gorund we have. The stuff that went through the Mequon- Germantown area last week pretty much did that, very little soil penetration.

One option you may want to look into is a Ross RootFeeder. I use it on my birch regularly, and have been getting the norway maple, crab and pagoda dogwood the past few weeks.

The RRF is a probe that screws on to the hose end and you can saturate a 12x12 volume of soil pretty quick.

 

[wysiwyg]

I've been using a Ross probe intermitently for about 10 years now. The problem with them is they don't work well (at least in our soil) when its rock hard. The water just shoots out of the hole a few seconds after it's turned on.

Now that I think about it, our green ashes are turning yellow as well...and just full of seeds like never before. So far the yellow is mainly in the top part of the canopy, not as bad near the bottom.

 

[John Paul Sanborn]

Could be you have the hose turned on too high for the water to move outwards well.

When real dry, I'll drill it in on high pressure, then, using a cock on the hose end, I'll reduce the flow.

Using it once a week on the birch I can feel when I get through the dry layer to the zone of moist soil when placing the probe in.

I'll let it run for around 15 min, with an egg timer, as I sit and read a book. Move it around the tree over a morning.

 

[wysiwyg]

Believe me, I've tried just about everything to get the Ross probe to work. The other complicating factor I forgot to mention was that our soil is full of rocks. Oftentimes it takes 3 or 4 "probings" to get it deep enough without hitting a rock. On the smaller trees the holes are so close together that the water just flows out of the other holes even on low pressure.

What I've done instead recently is use a wheelbarrow full of top soil to create a circular berm around some of the smaller trees I planted directly by nut or acorn, about 4 inches high and a diameter big enough to be outside the drip line. I flood the area 4 or 5 times over the course of a couple hours and am able to get the water to penetrate a couple feet deep.

For the more mature trees (> 4 years) I'm just going to continue to roll the dice and let nature take its course. As a country bumpkin I guess I value my well more than my trees.

Thanks for the help!