Yellowing of young Greenspire Linden Tree

aanderso12

I am very worried about our young Greenspire Linden tree that we just planted on the ground 6 days ago. It was very healthy, ~15 ft tall, and came in a 25 gallon pot. The hole was well dug with a mixture of garden soil and top soil to fill the area. The ground however is all clay. It has also been very hot (in the 90s) this week in Northeast Ohio (Zone 5b) so I have been keeping it watered with at least 1 gallon in the afternoon and the irrigation system waters it twice more. The soil reads that it is fully wet with a meter. The system does hit the leaves of the tree.

As you can see from the picture, the leaves are turning yellow. Actually, its only the middle of the tree. The leaves on the bottom half are still green and the top of the tree still has green leaves, its just the middle half. This started two days ago. What would cause the leaves to yellow? Could it be too much water/too little? Does it need to be treated for something? Could the irrigation system hitting the leaves effect the area? PLEASE HELP!!

Attached Thumbnails

 

Brent Ferris

It is probably a problem of too much water, and the different soil types. Clay soil absorbs water very slowly, and lets it go very slowly - tiny pores. So the water runs thru the garden soil -- quickly -- and very slowly tries to penetrate the clay soil. The water is likely building up in the bottom of the hole, and the tree is effectively drowning. Removing the excess water may help. Essentially, dig up the tree, remove the watery soil, let the root ball drain and replant. If possible add more clay to the soil mix you're giving to the tree. More clay will hold water better and more evenly, and give you a better idea of how often to water. Clay soils are often better watered 1 x per week -- giving the water time to percolate, be absorbed by the tree, and the excess drain away.

The hot temperatures exacerbate the problem. The tree wants more water, but the excess water is waterlogging the cells of the roots, and without enough oxygen, the roots can't function, and so even tho there is plenty of water, not enough can be absorbed.
If replanting helps, shading the tree may help with extreme temperatures. I am NOT thinking of a tarp or solid shade cover, but one that removes about 50% of the sun thru the day until the tree is established, or for at least July and August. If you can procure a short length (6 - 8 ft) of snow-fencing, and elevating it, this will allow sun on- sun off during the day -- that would be ideal. You could also make your own.

And while irrigating saves watering time, many systems only water for 20-30 minutes for an area, every day. This short watering time prevents water from penetrating the soil to any depth, so the roots have to grow to the surface to get water, and near the soil surface is the highest range of soil temperatures, especially in the daytime. SO the roots tend to die, and leave homeowners perplexed. THe better way -- ignoring water conservation decrees -- is to water for 5-8 hours one time per week, preferably at night to minimize evaporation, and enhance water penetration to lower soil levels, which leads to stronger, healthier trees.