PLANT PROTECTION 1 – Pests, Diseases and Weeds

PLANT PROTECTION 1 – Pests, Diseases and Weeds
Fig. 132. Foliar nematode (Aphelenchoides spp.
Foliar nematodes swim up stems and across leaves in films
of water and enter leaves and stems through stomates.
Upper left: Infested chrysanthemum leaves. Note wedgeshaped
area bordered by leaf veins in early stages of
infection. These are red, yellow or purple at first, turning
brown with age. Upper right: Portion of infested fern frond.
The dark areas between the veins are the infested areas.
Photo NSW Dept of Industry and Investment. Lower left: Symptoms may
be confused with overwatering and other environmental
problems. All symptoms suspected of being caused by
nematodes must be confirmed by laboratory investigation.
PhotoCIT, Canberra (P.W.Unger).
Fig. 133. Stem and bulb nematode (Ditylenchus dipsaci). Left: Bulbs cut longitudinally
to show browning of scales due to the nematodes feeding on the fleshy leaf bases. Do not
confuse with fungal rots. Cross section at neck of bulb shows rings of brown scales.
Right: Leaves showing raised blister-like streaks which are full of nematodes. Nematodes
move into new leaves causing blisters. Photo NSW Dept of Industry and Investment.
Nematode diseases 255