Q.2 Large Boxwood Plants, 25 Years Old, One Is Mostly Brown, The Other Green With Some Brown.
I have two boxwood plants that are over 25 years old. The plants get an accumulation of brown leaves with webbing on the limbs & I usually brush the plants with a broom to remove. This spring one plant had mostly brown leaves and stems. I started cutting back all of the totally brown stems in April and some now have green leaves but the plant doesn’t look well even with the green leaves. The other boxwood looks very green but has a lot of the brown dead leaves accumulating and a couple areas I have trimmed since they turned white. Both looked like the image 2112 last year. Any suggestions?
Certified GKH Gardening Expert
Yellowing and webbing on Boxwood can be caused by several factors. One common cause is the presence of spider mites, which are tiny pests that feed on the plant's sap and create fine webbing. Spider mite infestations can lead to yellowing of the leaves and overall decline in the health of the Boxwood. Other possible causes of yellowing and webbing include fungal diseases, nutrient deficiencies, and environmental stressors such as excessive heat or drought. It is important to identify the specific cause in order to implement appropriate treatment and prevent further damage to the plant.
Likely, it is one of two insects, and the lifespan of the shrub may be close to an end. They live around 20 to thirty years on average, but can live much longer with proper maintenance. Leaf miners and spider mites cause webbing, commonly. Neem oil and fungicides may be necessary.
These articles will offer some suggestions for these issues:
https://www.gardeningknowhow.com/ornamental/shrubs/boxwood/boxwood-spider-mites.htm
https://www.gardeningknowhow.com/plant-problems/pests/insects/spider-mite-control.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/azadirachtin-vs-neem-oil.htm
https://www.gardeningknowhow.com/plant-problems/pests/pesticides/neem-oil-uses.htm
