Problem hollies - Ask Extension
I have 2 Japanese hollies, one on each corner of the house, north side. One is a male, the other a female but I don't remember what type they are. The...
Knowledgebase
Problem hollies #239881
Asked April 27, 2015, 12:55 PM EDT
I have 2 Japanese hollies, one on each corner of the house, north side. One is a male, the other a female but I don't remember what type they are. They are about 20 years old. I have noticed the problem with blacking leaves for the past 3 years, gradually getting worse, and one holly especially has fewer leaves every year. We have tried spraying with Sevin and feeding with HollyTone but they continue to get worse.
They are about 6 ft tall each. They pretty much get full sun all day.
I am having problems with dwarf cypress and dwarf azaleas in the same bed, I had to send pictures of them in separate emails. I don't know if each of these is having it's own issue or is there a common problem across the bed.
Howard County Maryland
Expert Response
The primary problem with your holly is the presence and activity of scale insects, probably cottony camelia scale. These sucking insects produce a waste secretion known as 'honeydew'. This material is sweet and sticky and drops down onto the upper surfaces of the leaves below the scale insects. The honeydew, in turn, encourages the development of sooty mold which is the black material you witness on the leaves. Although the sooty mold is not a serious threat to the foliage, the scale insects will continue to weaken the tree and could lead to ultimate death of the tree.
You should begin a spray regimen using a summer dilution of horticultural oil. This can be sprayed throughout the growing season, however, do not spray the trees on sunny days when the temperatures exceed about 83 degrees F. Read the label carefully for instructions.
There also appears to be some winter damage to some of the foliage, but the tree should overcome that issue and put out new foliage this spring. Be prepared to provide supplemental irrigation to the tree throughout the summer and well into autumn, especially during extended dry spells.
LS
You should begin a spray regimen using a summer dilution of horticultural oil. This can be sprayed throughout the growing season, however, do not spray the trees on sunny days when the temperatures exceed about 83 degrees F. Read the label carefully for instructions.
There also appears to be some winter damage to some of the foliage, but the tree should overcome that issue and put out new foliage this spring. Be prepared to provide supplemental irrigation to the tree throughout the summer and well into autumn, especially during extended dry spells.
LS
