Bud Rot
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Figure 2. The spear leaf and next youngest leaves of this juvenile palm are exhibiting extensive necrosis due to a bud rot pathogen. Photo by M. L. Elliott.
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Figure 1. The spear leaf of this seedling palm has already died due to a bud rot pathogen. While the surrounding leaves appear healthy, the bud (apical meristem) of this palm has already rotted, and no new growth will occur. Photo by M. L. Elliott.
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Figure 4. The spear leaf and the next youngest leaves are desiccated and necrotic due to bud rot. Photo by M. L. Elliott.
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Figure 3. The spear leaf and the next youngest leaves are desiccated and necrotic due to bud rot. Photo by M. L. Elliott.
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Figure 6. The Cocos nucifera on the left side of this photograph had the spear leaf and surrounding youngest leaves die from a bud rot pathogen months prior to this photograph. These leaves have fallen out of the palm canopy. No new leaves have emerged because the bud (apical meristem) has also died. The Cocos nucifera on the right is a healthy palm. Photo by M. L. Elliott
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Figure 5. The initial site of infection is on the unopened leaf blade of the spear leaf. Photo by M. L. Elliott.
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Figure 8. Spore mass of Nalanthamala vermoesenii (=Gliocladium vermoesenii) on spear leaf tissue. Photo by M. L. Elliott
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Other common names
heart rot
No specific name can be assigned to a particular budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot until after the pathogen is determined.
Scientific name of pathogen
Nalanthamala vermoesenii: Kingdom Fungi, Imperfect Fungi (no known sexual state)
Phytophthora palmivora, Phytophthora katsurae: Kingdom Stramenopila, Phylum Oomycota
Thielaviopsis paradoxa: Kingdom Fungi, Phylum Ascomycota
Hosts
All palms are considered susceptible to at least one of the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot pathogens.
Distribution
Phytophthora palmivora has a worldwide distribution and is probably the most common budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot pathogen in the continental United States and Caribbean region, but Phytophthora katsurae is just as common in Hawaii.
Nalanthamala vermoesenii is an opportunistic pathogen with a worldwide distribution that is more likely to be observed in cooler climates (e.g., coastal California) or cooler seasons of the year (e.g., winter months in Florida).
Thielaviopsis paradoxa, which has a worldwide distribution, is reported in the literature as a cause of budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot, but it is not clear how often this pathogen causes this disease.
Symptoms/signs
The first symptom of a budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot is the discoloration and possibly a wilting of the spear leafspear leaf:
the younges emerging leaf that has not yet opened
(youngest, unopened leaf) (Fig. 1). The next youngest leaves may also appear discolored (chlorotic or necroticnecrotic:
see necrosis
) and wilted. Eventually, the spear leafspear leaf:
the younges emerging leaf that has not yet opened
(and sometimes the next youngest leaves) becomes desiccated, necroticnecrotic:
see necrosis
and collapses (Figs. 2-4). A close examination of the leaves prior to complete desiccation and collapse, especially the spear leafspear leaf:
the younges emerging leaf that has not yet opened
, often reveals blighted areas on the unopened leaf bladeleaf blade:
the broad, flattened distal portion of a leaf
(Fig. 5). As the disease progresses into the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
(heart or apical meristemmeristem:
the growing region of a plant, a special area of undifferentiated cells wherein new cells and organs are developed
), this tissue rots and the spear leafspear leaf:
the younges emerging leaf that has not yet opened
can be easily pulled from the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
. This rot is normally associated with a very foul odor. The rest of the leaves in the canopycanopy:
the cluster of leaves borne at the tip of the stem
will appear healthy; it is only the spear leafspear leaf:
the younges emerging leaf that has not yet opened
, the surrounding youngest leaves and budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
that are affected.
No new leaves emerge from the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
because the apical meristemmeristem:
the growing region of a plant, a special area of undifferentiated cells wherein new cells and organs are developed
is either rotted or no longer functioning as meristematic tissue. However, the leaves that were already present prior to budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
infection will remain green, appear healthy and remain attached to the trunk (Figs. 3 and 6). Eventually, these leaves will go from green to various shades of yellow and brown, but this is due to natural senescence or secondary leaf diseases and is not due to the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot disease.
If the diseased palm is still in a container or small enough in the field or landscape that the top of the canopycanopy:
the cluster of leaves borne at the tip of the stem
is still at eye level or below, the wilting and discoloration of the youngest leaves will be the first symptoms observed. However, if the palm is so tall that the canopycanopy:
the cluster of leaves borne at the tip of the stem
is above eye level, then the first symptom observed is usually a missing spear leafspear leaf:
the younges emerging leaf that has not yet opened
, the lack of new leaves emerging, or an open-topped crowncrown:
see canopy
(Fig. 6). The diseased palm did go through the discoloration, wilting and death of the youngest leaves, but that symptom was missed because the palm was too tall for easy viewing of these leaves.
In Hawaii, where budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot of Cocos nucifera is caused by Phytophthora katsurae, another early symptom of budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot is premature loss of fruits. The nuts develop distinctive large, brown lesions with green circles within these lesions (Fig. 7).
If the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot is caused by Nalanthamala vermoesenii, then a mass of pink-orange or pink salmon colored spores is usually evident on the affected tissue (Fig. 8).
In some cases, disease development may cease prior to death of the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
. In these situations, the palm may recover, but the first few new leaves that emerge usually appear abnormal - smaller in size, distorted shape, etc.
May be confused with
One of the symptoms of lethal yellowing or Texas Phoenix palm decline in Phoenix spp., Sabal palmetto, and Syagrus romanzoffiana is death of the spear leafspear leaf:
the younges emerging leaf that has not yet opened
. However, prior to death of the spear leafspear leaf:
the younges emerging leaf that has not yet opened
, you would observe early fruit drop, necrosisnecrosis:
dead tissue, usually desiccated and brown to gray in color
of the inflorescenses, and necrosisnecrosis:
dead tissue, usually desiccated and brown to gray in color
of about 25% of the lowest leaves in the canopycanopy:
the cluster of leaves borne at the tip of the stem
. You would not observe these symptoms in these species if the palms are affected by budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot.
Additional comments
Cold damage to the budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
(apical meristemmeristem:
the growing region of a plant, a special area of undifferentiated cells wherein new cells and organs are developed
) often results in a budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot due to opportunistic pathogens (various fungi and bacteria) invading the damaged budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
tissue. This budbud:
a common term for meristem; the specialized growing region of a plant containing undifferentiated cells from which new cells and organs are developed
rot is often not readily apparent for many weeks or even months after the cold damage occurred. There is a wide range of cold tolerance within the palm family. Also, palm species that might be tolerant of cold weather as mature specimens with elongated woody trunks and a full canopycanopy:
the cluster of leaves borne at the tip of the stem
may not be tolerant of the same weather event if the same palm species is a seedling, a juvenile, has a very short trunk or has had an excessive number of leaves removed.
