Q. Our young navel orange tree has a tall sprout coming up the middle. This is the first year the sprout has grown leaves; before it was just thorns. Should this sprout be cut off? This year’s crop of oranges tasted good.
All citrus trees are grafted onto hardy rootstock. The rootstock provides resistance to some soil-borne diseases and limits the tree’s mature height. When a shoot emerges from below the graft, it originates from the rootstock and should be removed since it is taking energy away from the productive part of the tree.
How can you tell where the graft is? Look at the lower part of the trunk and you will see either a kink or something that looks like a collar about a foot from the base. Sometimes there may be a few small shoots below this point and they can be easily snipped off. The shoot coming out of your tree is pretty substantial and, at first glance, looks like a regular branch. As you’ve noticed, this shoot originating from the rootstock is very thorny. This year, it’s growing leaves and plotting to take over, so get out that pruning saw and get rid of it.
Q. Several of our mature peach trees have severe peach leaf curl. I know it’s too late to spray, but is there anything we can do to minimize the damage this year?
Peach leaf curl is caused by a fungus (Taphrina deformans), which results in curled, puckered, and discolored (red) leaves on peach and nectarine trees. Sometimes only a few of a tree’s leaves are affected, but in severe cases, most of the leaves show these symptoms.
Due to the deformity, these leaves are not useful to the tree and will eventually drop. If the cool, wet weather subsides by this time, new healthy leaves will emerge. As you can imagine, replacing all those leaves is pretty rough on a tree, so I recommend removing most (if not all) of the fruit and applying some fertilizer to give it a chance to recover.
Once the tree shows signs of peach leaf curl, this is all you can do. After the icky leaves fall, dispose of them in the regular trash and keep them out of the compost pile.
Buy a bottle of fungicide that is labeled for peach leaf curl. The most common products consist of a fixed copper compound. Cop-R-Spray or Liqui-Cop are two widely used sprays. Buy it now while you still remember, because once dormant season comes you will have forgotten all about those ugly leaves. Set a reminder on Google Calendar as well. We like to spray toward the end of January since our first peach blossoms appear around Valentine’s Day. The spray must be applied before the tree comes out of winter dormancy. Once the tree experiences bud break (when you can see the first sliver of pink emerging from the buds), it is too late to spray.
Los Angeles County
mglosangeleshelpline@ucdavis.edu; 626-586-1988; http://celosangeles.ucanr.edu/UC_Master_Gardener_Program/
Orange County
ucceocmghotline@ucanr.edu; http://mgorange.ucanr.edu/
Riverside County
anrmgriverside@ucanr.edu; https://ucanr.edu/sites/RiversideMG/
San Bernardino County
mgsanbern@ucanr.edu; 909-387-2182; http://mgsb.ucanr.edu
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