Nematodes

Nematodes are tiny roundworms. They are often underrated because they operate mainly underground. Above-ground symptoms consist of stunting, reduced yield and drooping of leaves during midday with recovery at night. Often these symptoms are mistaken for mineral deficiency or drought. [1]
  1. Root knots
Caenorhabditis elegans_root knotsCause or pathogen: Caenorhabditis elegans, Meloidogyne incognita, Meliodogyne hapla, Meloidogyne javanica Description and Symptoms: Root knot nematodes embed themselves in roots and induce cannabis plants to form giant cells or syncytia. Syncytia swell into root galls and stimulate formation of rootlets, creating a bushy root. Meloidogyne incognita has been reported in southern fiber cultivators in Europe, Russia, Brazil and the southern US. Meliodogyne hapla and Meloidogyne javanica are common in the north. Recommendations: Some nematicides may help. [1]
  1. Stem nematode
Ditylenchus dipsaciCause or pathogen: Ditylenchus dipsaci Description and Symptoms: Ditylenchus dipsaci lives above the ground and does not infest rots. Initial symptoms arise in stems, branches and leaf petioles, which swell and become chlorotic. Plants are stunted. It has been described only in fiber hemp varieties in Europe. Recommendations: Cooler temperatures and lower humidity can suppress the reproduction and infestation rates of D. dipsaci. A nematicide fumigant that is specific to the Ditylenchus genus should be used. [2]
  1. Cyst nematodes (Heterodera schachtii, H. humuli), needle nematodes (Paralongidorus maximus), and root lesion nematodes (Pratylenchus penetrans)
Cyst nematode
Cyst nematode
Cause or pathogen: Heterodera schachtii, H. humuli, Paralongidorus maximus, Pratylenchus penetrans Description and Symptoms: Heterodera schachtii (cyst nematodes) – Stunted growth and yellowing are early signs of the disease. Infection can be confirmed by the presence of maturing cysts on plants’ roots. [3] Paralongidorus maximus (needle nematodes) – needle nematode has ectoparasitic habits and feeds on root tips causing elongate or knob-shaped swellings. [4] Pratylenchus penetrans (root lesion nematodes) cause necrotic lesions on the roots. [5] Recommendations: Some nematicides may help.   Sources 1. A review of Cannabis Diseases 2. Ditylenchus dipsaci 3. Heterodera schachtii 4. PARALONGIDORUS MAXIMUS 5. Pratylenchus penetrans   back-md

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