Certain
environmental factors influence Meloidogyne
spp development. They are moist soils and relative temperature. Some plants
penetration by root-knot nematodes occurs between 10 and 35°c, with the optimum
temperature at about 27°c depending on the species. Temperatures are broadly
divided into five (5) arbitrary phases:-
(1)
Non-lethal-low
temperatures at which activities is inhibited.
(2)
Optimum
temperatures- nematodes are not affected by this
temperature, so
the activities of the nematodes are at maximum.
(3)
Non-lethal
high temperature at which activity is inhibited.
(4)
Lethal
low temperature – the temperature can kill the nematode.
(5)
Lethal
high temperature-at high temperature, its nematode is killed
automatically.
Also water is one of the environmental
factors that affect nematode population, extreme moisture conditions in the
soil does not favor nematodes, example: flooding may kill the nematodes and
they are used as one of the methods of control of nematode attack. Soil pores
and aeration, which is the porosity of the soil and the oxygen and carbon
dioxide content of the soil respectively are major factors that influence nematode population
and the rate of attack to our plants.
Chemicals in the soil solution may affect
plant nematode population indirectly through plant growth and directly by
acting as orientation stimuli. Also conditions like infected volunteer plants,
monocultures, weeds in the fields, continuous growing of susceptible crops
without rotation.