Aphelenchoides fragariae

Aphelenchoides fragariae	Contents	Rev 11/20/2008
Strawberry Foliar Nematode	Classification	Hosts
	Morphology and Anatomy	Life Cycle
Return to Aphelenchoides Menu	Economic Importance	Damage
	Distribution	Management
Return to Aphelenchoididae Menu	Feeding	References
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Classification:

       Tylenchida
       Aphelenchina
         Aphelenchoidea
          Aphelenchoididae
           Aphelenchoidinae
                Aphelenchoides fragariae

Morphology and Anatomy:

Aphelenchoides fragariae is 0.45-0.8mm long.

Distribution:

Temperate and tropical regions, moist conditions.

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 CO₂is common in soil nematodes.

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Hosts:

250 hosts, including fern, begonia, and strawberry.

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Life Cycle:

Sexually reproducing; males required.

Life cycle 10-13 days.

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 suggests there may be an insect vector but, as yet, there is no evidence.

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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, France)	A. fragariae symptoms on Begonia (M. Ritter, France)

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

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Management:

Sanitation:

Roguing plants, burning infested material, starting/replacing with healthy stock, general sanitation.

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.