Palm Bud Rot/ Heart Rot
(Phytophthora palmivora)
in the Low Desert

HOST:

There have been only two records of this disease documented on California and Mexican Fan palms in Arizona in the last 50 years. There has never been a documented case of bud rot in Queen Palms.

SYMPTOMS:

The yellowing or stunting of fronds, sometimes followed by their collapse, which is often attributed to "Bud Rot" or "Heart Rot" is more likely due to either poor watering practices or a Manganese deficiency.

CAUSE:

Except in very humid tropical areas with high rainfall, it is unlikely that phytophthora, a water-loving organism, would be a problem in the crown of palms. It is more likely to cause a root rot in over-watered plants or plants in soils with poor drainage.

MANAGEMENT:

Fungicides are often recommended as a preventative measure or as a treatment when palm crowns begin to look stressed. However current knowledge suggests that any response of declining palms attributed to fungicide treatment probably is the result of a general improvement in care (increased water, fertilizer) rather than to the fungicide.

Apply a fertilizer with micronutrients (including Manganese) at the rate prescribed on the label. Ensure that the entire root zone is watered deeply and allowed to dryout between waterings.

To Gardening and Landscaping in Maricopa County, AZ