''Pestalotiopsis palmarum'' is the causative agent of a

fungal disease A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from th ...

banana A banana is an elongated, edible fruit – botanically a berry – produced by several kinds of large herbaceous flowering plants in the genus ''Musa''. In some countries, bananas used for cooking may be called "plantains", distinguis ...

coconut The coconut tree (''Cocos nucifera'') is a member of the palm tree family ( Arecaceae) and the only living species of the genus ''Cocos''. The term "coconut" (or the archaic "cocoanut") can refer to the whole coconut palm, the seed, or the ...

and

Date palm ''Phoenix dactylifera'', commonly known as date or date palm, is a flowering plant species in the palm family, Arecaceae, cultivated for its edible sweet fruit called dates. The species is widely cultivated across northern Africa, the Middle Eas ...

s . The fungus causes leaf spots, petiole/

rachis In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this c ...

blights and sometimes bud rot of palms. Unlike other leaf spot and blight diseases, ''Pestalotiopsis palmarun'' attacks all parts of the leaf from the base to the tip. Whereas most diseases only infect the leaf blade or the leaf petiole.

Host

The fungus has been isolated from a wide variety of palm tissue. The fungus is not host specific so the disease could be present in many more types of

palm Palm most commonly refers to: * Palm of the hand, the central region of the front of the hand * Palm plants, of family Arecaceae **List of Arecaceae genera * Several other plants known as "palm" Palm or Palms may also refer to: Music * Palm (ba ...

, but further research needs to be done. The fungus has also been known to infect pygmy date palm (''

Phoenix roebelenii ''Phoenix roebelenii'', with common names of dwarf date palm, pygmy date palm, miniature date palm or robellini palm, is a species of date palm native to southeastern Asia, from southwestern China (Yunnan Province), northern Laos and northern V ...

'') and has been a big problem in

Florida Florida is a state located in the Southeastern region of the United States. Florida is bordered to the west by the Gulf of Mexico, to the northwest by Alabama, to the north by Georgia, to the east by the Bahamas and Atlantic Ocean, and to ...

during the winter months. Some varieties of bananas have also shown symptoms of the disease, but it is unclear if it is in fact ''Pestalotiopsis palmarum''.

Symptoms

It has been shown that the fungus usually requires wounds to infect the plant and necessary for the fungus to develop. The first symptoms of ''Pestalotiopsis palmarum'' begin as very small yellow, brown or black discoloration of the leaves. The disease can be restricted to the leaf blade or may only appear on the petiole and rachis right away. Spots and discoloration areas can be smaller than in size, but under optimal conditions can grow much larger eventually forming lesions. The spots will often turn a grayish color and will be outlined in black. Extreme wilting and a drying appearance on the leaves is also a major symptom of ''Pestalotiopsis palm''. In mature palms, if the fungus is limited to only leaf spots, the disease may not be very serious and damaging. However, the fungus can severely affect juvenile plants if only a few leaf spots are present because they have yet to develop a trunk and only have a few leaves.

Management

Wind and water movement easily disperses

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s of ''Pestalotiopsis palmarum'' so sanitation and irrigation management can be proven to be critical in preventing the movement of the disease. Wounds and damage to the plant offer easy access for the fungus so the limitation of human and insect activity can be very beneficial. Limiting the length of time that the leaves are wet when exposed to high humidity levels also reduces the risk of inoculation. So eliminating overhead irrigation can prevent infection on leaves when there is favorable humid weather. Nutrient management is also very important in controlling ''Pestalotopsis palmarum''. Nutrient deficiencies can cause

chlorosis In botany, chlorosis is a condition in which leaves produce insufficient chlorophyll. As chlorophyll is responsible for the green color of leaves, chlorotic leaves are pale, yellow, or yellow-white. The affected plant has little or no ability to ...

and

necrosis Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...

of leaf tissue which then in turn creates a wound necessary for disease inoculation. Based on the amount of disease on the leaves, pruning the leaves may treat the disease, but one needs to decide if pruning the leaves is worth the nutrient deficiency that could follow depending on the growth stage of the plant.

Fungicide Fungicides are biocidal chemical compounds or biological organisms used to kill parasitic fungi or their spores. A fungistatic inhibits their growth. Fungi can cause serious damage in agriculture, resulting in critical losses of yield, quality, ...

s are also available for managing the disease, but alone will not solve the problem. Fungicides will prevent infection of healthy leaves, but infected leaves will stay infected until the leaf dies. Using multiple techniques for managing ''Pestalotiopsis palmarum'' at the same time is recommended for optimal management of the disease.

References

External links

USDA ARS Fungal Database
{{Taxonbar, from=Q7171476 Fungal plant pathogens and diseases Banana diseases Coconut palm diseases Palm diseases palmarum