Aphelenchoides fragariae		Contents		Rev 06/13/2022
Strawberry Foliar Nematode  Strawberry Crimp Nematode		Classification		Hosts
		Morphology and Anatomy		Life Cycle
Return to Aphelenchoides Menu		Economic Importance		Damage
		Distribution		Management
Return to Aphelenchoididae Menu		Feeding		References
		Go to Nemaplex Main Menu		Go to Dictionary of Terminology

Classification:

       Tylenchida
       Aphelenchina
         Aphelenchoidea
          Aphelenchoididae
           Aphelenchoidinae

                Aphelenchoides fragariae (Ritzema Bos, 1891) Christie, 1942

Various common names include Strawberry crimp nematode, Strawberry spring dwarf nematode, Foliar nematode

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Morphology and Anatomy:

Aphelenchoides fragariae is 0.45-0.8mm long.
	Reported median body size for this species (Length mm; width micrometers; weight micrograms) - Click:

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Distribution:

Temperate and tropical regions, moist conditions. Widespread in the United States, Europe and Asia as a pest of many plants and seems well adapted to tropical and temperate climates (Scheck, 2021).

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Economic Importance:

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Feeding:

Endoparasite in leaves, but also feeds ectoparasitically on leaf and flower buds in strawberry, for example.  

Nematode enters leaves through stomata or directly.

Aphelenchoides fragariae can swim rapidly; may be negatively geotropic.

Swiss scientist, J. Klingler studied entry of stomata by Aphelenchoides fragariae.  The nematodes aggregated around slits in plastic film even when there were no gases emerging, suggesting recognition of a tactile stimulus.  They had negative or indifferent reaction to oxygen, but strong positive reaction to carbon dioxide emerging from the slits.

That situation would occur at night - no photosynthesis, so CO₂ from respiration would emerge from stomata.  Also at night, dew would provide a moisture film and facilitate nematode movement on the leaf surface.   Note, incidentally, that a positive attraction to CO₂ is common in soil nematodes.

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Hosts:

More than 250 hosts, in 47 families, including fern, begonia, and strawberry.

The following are listed as hosts in various literature sources:

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Life Cycle:

Ecophysiological Parameters:

• Sexually reproducing; males required.  
• Life cycle 10-13 days. Both males and females present; sexually reproducing.
• Female produces about 30 eggs.  
• Survives in soil about 3 months, longer in plant tissue.  Overwinters in dead plant tissues in soil, and also in buds and growing points.
• May overwinter in weeds around strawberry fields (Westerdahl); Maggenti suggested there may be an insect vector but, as yet, there is no evidence.   
• Aphelenchoides fragariae may complete its entire life inside leaves or on the surfaces of the plant hosts. Nematodes swim rapidly on wet leaf sufaces; they can be splashed to new plants or to distant parts of the same plants by falling rain or overhead watering. They enter leaves through stomata or through wounds.
•  The female lays eggs in the intercellular spaces of leaves. The eggs hatch and produce the four juvenile stages and adults all inside the leaf. The nematodes overwinter as adults in dead leaves or between the scales of buds of infected tissues. Adults and fourth-stage juveniles can overwinter in an anhydrobiotic state within dried plant tissue and can survive that way for up to three years.
• In the spring they become active and feed ectoparasitically on the epidermal cells of the organs in their vicinity. Thus, stem areas, petioles, and leaves near infested buds show brown scars consisting of groups of cells killed by the nematodes.

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Damage:

Nematode feeding causes blotches and necrotic lesions between veins on fern leaves which start as water-soaked spots and then turn brown. 

In strawberries, A. fragariae causes malformed leaves with crinkled edges. (G. Caubel)	A. fragariae symptoms on Begonia (M. Ritter)

Nematode injury to leaves: Drawing by Charles S. Papp, CDFA

Disease symptoms on strawberry are called spring dwarf, spring crimp and red plant.

Endoparasitic activity of A. fragariae causes shoot malformations including twisting and puckering of leaves, discolored areas with a hard and rough surface, undersized leaves with crinkled edges, reddening of petioles, tight aggregation of crowns, shortening of internodes on runners, reduced flower trusses with only one or two flowers or flowers aborted, and death of the crown bud (Maas, 1998; Ploeg and Westerdahl, 2018).

Ectoparasitic feeding on folded crown and runner buds causes small dry, brown areas that are seen on expanded leaves usually near the mid-rib. Occasionally the nematodes are found in strawberry fruit pulp (Tacconi, 1972).

On flowering ornamentals such as violets, anemone and begonia, the feeding areas of foliar nematode appear as irregular, water-soaked patches later turning brown, violet, or black. The affected areas are limited by the leaf veins.

The nematode causes die-back disease of lilies; leaves, flower buds and fruits turn brown and die (Daughtrey et al., 1995). Ferns develop water-soaked, often chevron-like stripes on fronds as movement of the nematodes seems to be delimited by vein. The stripes turn brown in summer when the fern is the driest (Sandeno and Jensen, 1962).

The nematode is easily spread to new hosts when in the anhydrobiotic condition, or by movement of infected but asymptomatic planting stock.

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Management:

Sanitation:

Roguing plants, burning infested material, starting/replacing with healthy stock, general sanitation. Nematode-free planting stock may be based on inspection by regulatory agencies. For example,   foundation, registered, and certified nursery stock may be inspected and tested for viral, fungal, and bacterial pathogens, nematodes, and varietal purity.

Disinfestation:

Hot water dips can be used on strawberry plants (15 min. at 47 C.), but cultivars and requirements change - current experiments are being conducted by Westerdahl.  

Plants must not be damaged, and yield must not be affected negatively.  

Hot water treatment may be used for other crops, also.  

Chemical control can be used; e.g., Parathion as a foliar spray. 

Host Plant Resistance, Non-hosts and Crop Rotation alternatives:

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References:

Bohmer B, 1981. The harmful effect of Aphelenchoides fragariae and A. ritzemabosi on Fragaria ananassa. Gesunde Pflanzen, 33(5):113-117

CABI Crop Production Compendium 2021. Apehelenchoides fragariae. https://www.cabi.org/cpc/datasheet/6381 Accessed 9/29/21

Chitambar, J. J., Westerdahl, B. B., and Subbotin, S. A. 2018. Plant Parasitic Nematodes in California Agriculture. In Subbotin, S., Chitambar J., (eds) Plant Parasitic Nematodes in Sustainable Agriculture of North America. Sustainability in Plant and Crop Protection. Springer, Cham.

Daughtrey, M. L., Wick, R. L., and Peterson, J. L. 1995. Compendium of flowering potted plant diseases. American Phytopathological society, St. Paul, MN

EPPO Global Database. 2021. Aphelenchoides fragariae https://gd.eppo.int/taxon/APLOFR. Accessed 9/29/2021/21

Goodey, J. B., M. T. Franklin, and D. J. Hooper. 1965. T. Goodey's: The Nematode Parasites of Plants Catalogued Under Their Hosts. Commonwealth Agricultural Bureaux, Farnham Royal, Bucks, England. Third Edition

Ibrahim, S. K., R. N. Perry and D. J. Hooper. 1994. Use of esterase and protein patterns to differentiate two new species of Aphelenchoides on rice from other species of Aphelenchoides and from

Kohl, L. M. 2011. Foliar nematodes: A summary of biology and control with a compilation of host range. Online. Plant Health Progress doi:10.1094/PHP-2011-1129-01-RV

Maas, J.L., Ed. 1998. Compendium of Strawberry diseases 2nd Edition. APS Press. Nemaplex UC Davis Nemabase 2010. Aphelencoides fragariae. Accessed 9/29/21

Maeseneer, J. D. 1964. Leaf-browning of Ficus spp., new host plants of Aphelenchoides fragariae (Ritzema Bos). Nematologica 10:403-408.  

Mor, M., and Y. Spiegel. 1993.  Ruscus hypophyllum: a new host for Aphelenchoides fragariae. Journal of Nematology 25:312-313.  

Ploeg, A. and Westerdahl, B. B. 2018. UC IPM pest Management Guidelines: Strawberry Nematodes. UC ANR Publication 3468

Riedel, R. M. and P. O. Larsen. 1974. Interrelationship of Aphelenchoides fragariae and Xanthomonas begoniae on Rieger begonia. Journal of Nematology 6:215-216.

Sandeno, J.L., and Jensen, H. J., 1962. A foliar nematode disease of western sword-fern, Polystichum munitum. Plant Disease Reporter, 46(10):699-701.

Scheck, H.J. 2021. California Pest Rating Proposal for Aphelenchoides fragariae (Ritzema - Bos, 1891) Christie, 1932 Strawberry crimp nematode, Strawberry spring dwarf nematode, Foliar nematode CDFA, Sacramento.

Siddiqui, I. A., S. A. Sher and A. M. French. 1973. Distribution of Plant Parasitic Nematodes in California. State of California Department of Food and Agriculture, Division of Plant Industry. 324p.

Tacconi R, 1972. Infestations of Aphelenchoides fragariae, Aphelenchoides ritzemabosi and Ditylenchus dipsaci on strawberry in some Italian provinces. Redia, 53:313-319

USDA Phytosanitary Certificate Issuance and Tracking System, Phytosanitary Export Database (PExD) Harmful Organisms Database Report. Aphelenchoides fragariae. Accessed 9/29/2021

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Copyright © 1999 by Howard Ferris.
Revised: June 13, 2022.