Fusarium wilt phoenix canariensis

Therefore, a laboratory diagnosis is required to confirm Fusarium wilt. To confirm the field diagnosis, a laboratory must isolate a Fusarium oxysporum -like fungus from the affected leaf tissue and then conduct a molecular test on the isolated culture to confirm it is f.

The best tissue to send for a diagnosis is the petiole or rachis from a leaf exhibiting the typical symptoms of one-sided wilt. A dead leaf is not acceptable.

Molecular confirmation of the isolated fungus is critical. There are numerous Fusarium oxysporum isolates that do not cause disease but may be associated with palm material.

Unfortunately, it is not possible to separate pathogenic isolates from nonpathogenic isolates based on their appearance in culture. Thus, isolating a fungus that looks like F. The fungus growing on the culture plate must be subjected to a molecular test that is specific for F. Be sure to discuss the problem with the clinic staff before resubmitting samples.

If no symptomatic leaves are available, wait until new symptoms develop before resubmitting. There are no cures for this disease. Fungicides have been evaluated, but none have been effective. Disease management is based solely on disease prevention. The fungus is most likely moved between distant locations by plant material, both live plants and probably seed. This is probably how the disease was first introduced and reintroduced into Florida. Unpublished research from both Florida and Australia has demonstrated the fungus can colonize palm seeds.

This makes it critical for palm nurseries to know that their seed and stock plants are coming from a disease-free source.

Likewise, nursery growers, landscape architects, and installation companies should examine and select Canary Island date palms while they are still in the field or on site at a container nursery and make this inspection prior to any trimming of older leaves so the plants can be inspected for symptoms. Then, they should either monitor the trimming of these palms to ensure they are trimmed correctly or trim them at the installation site using the correct procedure discussed below.

Once the disease is established in a landscape or nursery, the disease appears to primarily be transmitted from palm to palm via leaf pruning equipment Figures 5 and 6. The fungal pathogen is in the vascular tissue of the leaf. Equipment used to remove leaves from an infected Canary Island date palm chain saw, lopper, pruning shear, handsaw, etc.

If that equipment is not cleaned and disinfected, the next Canary Island date palm and perhaps other Phoenix species pruned by this equipment will be exposed to this fungal-infested leaf material. It is important to note that a palm could be infected but appear healthy symptomless because the disease has not developed to the point that leaf symptoms are being expressed. Unfortunately, it is not known how long this infected but symptomless stage of the disease lasts.

It could be 6—18 months. Thus, the fungus could still be moved from palm to palm by pruning infected but symptomless leaves! This means Canary Island date palms should be pruned with either new pruning tools or clean, disinfected tools, both in the landscape and nursery.

This applies to all Canary Island date palms, diseased and healthy. Either a new pruning tool or a clean, disinfected pruning tool should be used for each individual palm.

Pruning should be limited to once each year. Furthermore, pruning should be restricted to removal of only dead or dying leaves. Severe pruning, such as "hurricane cuts" or "pineapple cuts," weakens trees and increases the risk of pathogen transmission.

Pruning should be viewed as a risk factor for Fusarium wilt disease transmission and not as a benefit to the Canary Island date palm. Table 1 is a list of materials that can be used as disinfecting agents. Brush the tool blades clean of debris before placing in the disinfectant solution. For chain saws, it is recommended that they be taken apart and both the chain and bar soaked. By having multiple pruning tools, one tool can be soaking in the disinfectant solution in a bucket while the other tool is used for pruning.

Alternatively, a newly developed pruning saw disinfecting tube with disinfectant solution can be attached to your belt www. The disinfectant solution should be replaced at least every 10 trees or every 2 hours. Rinse tools with clean water before pruning.

The following is a management suggestion: For the initial installation of a Canary Island date palm, it is normal to remove a large number of fronds. Using a handsaw would be time consuming, so either use a new chainsaw or disinfect the chainsaw between each palm.

After installation, the number of leaves pruned should be limited as only dead leaves should be removed. This can be accomplished with a new pruning tool for each palm. While this is an extraordinary measure, it is inexpensive disease prevention management for extremely valuable palms. A mature Canary Island date palm that has died from Fusarium wilt is expensive to remove and expensive to replace.

It is certainly more economical to prevent the disease than deal with the deadly consequences, especially if there are multiple Canary Island date palms in the landscape Figure 6.

Using a new pruning tool or disinfecting the pruning tool is inexpensive in comparison to a devastated landscape. Again, this is a disease without a cure. In a nursery situation, diagnosis of this disease effectively destroys the crop as the plants are unsaleable and must be destroyed. In the landscape situation, the palm eventually dies and must be removed. In both situations, but especially the nursery situation, the diseased palm s should be removed and destroyed immediately.

Be very careful not to distribute potentially fungal-infested soil or potting mix in the nursery. Surrounding Canary Island date palms should be monitored closely because it is quite likely they could be infected. The diseased palm should be incinerated or placed in a landfill. If this is not possible as is the case in many Florida counties , then be sure the palm is not chipped and recycled for mulch in the landscape. Instead, chipped material should be placed in a compost pile.

Chain saws and other tools used for removal must be brushed free of plant material and disinfected as described previously. Chlamydospores of Fusarium oxysporum f. Experimental and observational evidence has shown the potential for infecting palms, especially seedling palms, with this fungus via the root system.

Therefore, it would not be prudent to plant a Canary Island date palm back into a site where Fusarium wilt killed the previous palm s. It is not known how far away from the potentially fungal-infested site one must move before it is safe to plant a Canary Island date palm.

Feather, T. University of California, Riverside, CA. Munnecke, and J. Plyler, T. Simone, D. Fernandez, and H. Simone, G. Plant Pathology Mimeo Elliott, T. Broschat, J. Uchida, and G.

Simone, 17— Smith, D. Smith, and P. Summerell, B. Kistler, and L. Nelson Memorial Symposium , edited by B. Summerell, J. Leslie, D. Backhouse, W. Bryden, and L. Burgess, — It is suggested that the solution be replaced after 10 trees or every 2 hours. Rinse the tool with fresh water after soaking. The leaflets on the opposite side of the rachis will be a healthy green color Fig. A reddish-brown or dark-brown stripe will be observed on the petiole and rachis of the affected frond, on the same side where the first dead leaflets appear Fig.

This streak may run the full length of the petiole and rachis , or just a portion of it. Internal discoloration will be observed in cross-sections of the discolored petiole and rachis Fig. Eventually the leaflets on the other side of the rachis will turn brown also, and the entire leaf dies.

The disease symptoms normally begin on the lowest oldest leaves and then move up the canopy , progressively killing younger and younger leaves. For some leaves, the leaflets may begin turning brown at the leaf tip and on both sides at once, rather than just on one side.

In all situations, the spear leaf is the last leaf to die. Fusarium wilt of Canary Island date palm often progresses at a relatively slow rate, and the palm can survive for as long as two years after initial symptom development. Since the primary method of pathogen transmission between Phoenix canariensis is pruning tools, it is not uncommon to see a landscape of Phoenix canariensis in various stages of disease development Fig.

Petiole rachis blight causes the same leaf symptoms in Phoenix canariensis. Laboratory diagnosis is necessary to confirm which pathogen is responsible for the symptoms.

It is possible for a Fusarium wilt pathogen and a petiole rachis blight pathogen to be present in the same tissue. Fusarium wilt caused by Fusarium oxysporum f. While this disease has been artificially induced on Phoenix dactylifera , it has not been observed to occur naturally. Three other Fusarium oxysporum formae speciales occur on palms. Fusarium oxysporum f.

Figure 1.