Root Rot in Arborvitae

Appearance

• Spotting root rot in an arborvitae requires looking at the plant for skinny roots that are brown, soft and are easy to pull away, which are signs of decomposition. A healthy arborvitae, on the other hand, bears skinny roots that also have a brown outer layer but feature a white interior and white tip. In addition, root rot results in foliage that is dried out, wilted and yellow.

Causes

• Compact soil -- which contributes to poor air flow around tree roots -- along with arborvitae root balls that are situated too deep in the planting soil are major causes of root rot in an arborvitae. In addition, clay soil is prone to becoming too water-saturated because it retains water longer and offers little aeration, so an arborvitae planted in clay soil is susceptible to root rot.

Other Causes

• Overwatering an arborvitae using a drip or sprinkler system potentially leads to root rot in these plants. This especially is a problem if air temperatures around the arborvitae are warm and the soil does not drain well. If not enough air gets to an arborvitae’s roots due to the presence of too much mulch in the area, this also causes root rot.

Control

• The best way to control root rot in an arborvitae is to not saturate the plant’s soil when watering. In addition, repositioning the arborvitae’s root ball so that the top of the ball is less than 2 inches below the soil’s surface is necessary for this plant to thrive.

  Getting rid of root rot -- especially phytophthora root rot, which is caused by the fungi Phytophthora cinnamomi -- sometimes requires the regular application of a root rot fungicide, according to the manufacturer’s instructions. Prior to applying this type of chemical to the arborvitae, sending a sample of your plant to a local soil and plant laboratory to confirm the presence of root rot is essential to ensure you use the correct chemical on the plant.