Hello,
I am in Zone 3a, I planted a Skybound cedar in late May. And it is now end of July and the tree has several browning/yellowing branches. I am afraid to fertilize it at this time, as everything online warns against fertilizing in the late July. But I read one of your other posts (for browning emerald cedars) which recommends fertilizing in the fall with a slow release N P fertilizer in order to provide a ‘spring boost’….
I would really appreciate some guidance here! If a cedar is really struggling, is it OK to fertilize in late July or August? And if so, with what NPK ratio? Or do I wait until the fall – October (?) and fertilize with something like 10-10-10.
You can also tell from the attached photo (which shows the top half of the tree), that the branches are quite floppy. Can we also prune this in late summer??.
Thank you!
Without more information about the soil, light condition and other factors about the location, it is a challenge to diagnose exactly what is causing the browning. However, I think that fertilizer is not the answer, especially if you regularly compost the bed in which the tree is planted.
It is more likely due to one of these issues:
Moisture management, either too dry or too wet. Dig down a few inches and feel the soil. If dry, water regularly. If very wet (and that may be the case given the recent massive rainstorm), stop watering and check that the roots are not mushy and rotted. Unfortunately, the fungus that causes root rot will kill the plant. This is very common in heavy clay soils. And lack of proper root growth may explain why the branches are flopping.
Insect infestation: Cedars are subject to attacks from aphids and other insects.
As we explained to a previous inquirer, “You should be able to see small tiny white eggs on the underside of the leaves and shiny honeydew which is secreted by aphids. Using a garden hose with a high pressure nozzle to knock off the aphids is an environmentally safe way to get rid of them, although this method requires a thorough job so you don’t leave any insects behind on your trees. This article from the University of Maryland may be helpful in identifying and treating for aphids should these be the culprit.”
In the same response, we described Cedar Leafminers (Argyresthia spp.). “Larvae of this insect overwinter in the leaflets and in the spring they damage the foliage by “mining” through the leaves. By the end of May these caterpillars have formed cocoons and small white moths emerge by the end of June. This website from the Ontario Government describes these insects in more detail. Pruning is one way of getting rid of any potential eggs prior to next spring when the cycle begins again.”
Spider mites also attach cedars. Again, we previously provided detailed information, “Spruce spider mites, Oligonychus ununguis, and red spider mites feed on the needles of arborvitae causing them to turn gray or brown. They can be detected by the webs that they spin over the branches. Their piercing-sucking mouth parts enable them to suck the juice from the foliage.
Light infestations can be taken care of by spraying plants with a forceful stream of water including the underside of the foliage. Do this every day for three days. If mites continue to be a problem, spray with insecticidal soap every three to five days for two weeks in order to interrupt the cycle of eggs hatching. It is advisable to spray the soil as well as the plant.”
I would recommend that you take a very close look at the tree, perhaps with a magnifying glass, to find any insect pests that might be causing the problem.
As for the pruning, if you find the brown branches very unsightly, you could remove them now, but it would be better to leave pruning until the tree is dormant, late winter / early spring. At that time, if the tree seems to be recovering, I would only shear it lightly.
In addition, questions about browning cedars are one of the most asked . If you enter “browning cedars: in the Find It Here box on our home page, you will see many, many responses we have provided.
If none of these suggestions seem to be relevant to your situation, please post your question again, with more details about the growing conditions.