Abstract:
Root knot nematodes are capable of infecting over 3000 host plants including, ornamental plants. It is
widely distributed and damaging Zinnia elegans flowers. Widespread dissemination and lack of
information regarding this ornamental plant damage due to plant-parasitic nematodes is attributed to
demand research for agronomic crops and an important avenue for distribution of other plant-pathogenic
organisms. The aim of this study was to identify and evaluate the Pathogenecity of Meloidogyne arenaria
on common zinnia, and to manage the nematode using coffee husk and biochar amendments. All
experiments were conducted in Jimma University College of Agriculture and Veterinary Medicine
(JUCAVM). The host status experiment was carried out on common zinnia plant on infected soil under
greenhouse. Pathogenecity study and nematode pest management experiments per pot were laid out using
completely randomized design (CRD) under greenhouse condition at JUCAVM. Seedlings with four true
leaves were inoculated with J2 a week after transplanting. Data on number of eggmass and root gall,
final nematode population, reproduction factor, plant height, root length, leaf number, fresh weight of
shoots and roots were collected from each treatment in all experiment after two months of inoculation.
The results of host status showed that the growth rate of plant (height, root length, leaf number, fresh
weight of shoots and roots) were increased with time. Aboveground symptoms developed over time due to
infection. The maximum nematode populations (26715), numbers of root gall (506) and eggmass (483)
were noted 16th week after infection. The result of Pathogenecity study showed that the initial inoculum
level increases the number of galls, eggmass and final nematode population. The highest number of
galls122.0), eggmass (66.33) and final nematode population (25114.3) were noted on 16J2/g soil, but for
nematode reproduction factor was achieved at inoculum level of 2 J2/g soil (6.45). Application of coffee
husk and biochar amendment reduced the root galling and final populations of M. arenaria compared
with control. The lowest nematode populations were recorded at 4:1 ratio from coffee husk and biochar
(200,925) respectively while the highest was noted on non-amended plants (29695). Coffee husk was
more effective than biochar in reducing population of nematodes. Amendment of soil with coffee husk and
biochar may provide practical control of root knot nematodes as a part of integrated management system.
However, further research is needed to evaluate their efficacy under field condition.
