الفهرس 
CHAPTER 1. IntroductionOnly 14 pages are availabe for public view
 |  | from | 202 |  |  |
| | | from | 202 | | |
Abstract
Nematodes of the genus Meloidogyne (RKN) are very
destructive pests that have a wide host range on horticultural and eld
crops causing yield losses of up to 45-60 per cent. The most important
nematode pests of potatoes in Egypt are Meloidogyne species
(principally Meloidogyne incognita and M. javanica) which infest roots
and tubers, causing root injury that severely reduces yields and may
accelerate the ”early dying disease.” Root-knot nematode galling of
tubers is a serious quality defect. Several control measures were
employed to control root-knot nematodes in infested areas. The
traditional method of nematode control is based mainly on chemical
nematicides. However, the potential negative impact on environment
and ineffectiveness after prolonged use have led to a total ban or
restricted use of most chemical nematicides and an urgent need for
safe and more effective alternatives. Biocontrol as an integral part of
management is an attractive option for plant parasitic nematodes that
should be pursued besides the cultural practices of crop rotation and
organic amendments. Using of biological pesticides, either of
bacterial or fungi origin, and the addition of organic material to the
soil can be an effective alternatives to the environmentally unsafe
chemical treatments that are used to control plant parasitic
nematodes.
Therefore, the present study analyzed the suppressive effects of
some commercial formulations of biological pesticides, either of
bacterial or fungal origin, on the soil populations of the second-stage
juveniles of root-knot nematode, Meloidogyne spp., in potato fields.
Also, we evaluated the efficacy of the addition of some organic
materials to the soil, either alone or combined with the tested
biological products on the occurrence of nematode density. Four
cultivars of potato were planted during 2016/2017 season.
We hypothesized that the addition of organic materials, either
alone or mixed with selected biopesticides, could provide faster and
better nematode suppression attacking potato. The present study was
carried out on potato, Solanum tuberosum L., infesting with damaging
populations of root-knot nematodes, Meliodogyne spp., under field
conditions at Meeleg valley, Shebin El-Kom, Menoufia, during
2016/2017 season. Four cultivars of potato were planted, viz. Spunta
The products we tested were: Dipel® (a biological pesticide
containing the naturally occurring microorganism, Bacillus
thuringiensis subspecies kurstaki (Btk)); NemaFree® (a biological
pesticide containing bacteria, Serratia sp.); Mycorrhizeen® (a
biological pesticide containing fungus, Arbuscular mycorrhizal); and
NemaStop® (a plant-based biological product combined with fatty
acids with claims of nematode suppression). Additionally, we tested
some biofertilizers (Nitrobein® and Phosphorin®), organic compost,
and poultry manure. Treatments were compared to untreated control
plots and plots treated with the labeled rate of Counter® l5 G. Each
experimental product was applied at rates corresponding to the
manufacturer’s recommendations. There were three replications of
each treatment.
Therefore, the main purposes of the present study was to:
Evaluate the sensitivity of some varieties (cultivars) of potatoes
commonly grown in Egypt to the infection of nematodes.
Evaluate the effectiveness of certain commercial formulations of
biological pesticides of bacteria, fungi, or plant origins as
alternatives to the conventional nematicides, especially against
the most abundant nematode genera, RKN, Meloidogyne spp.
Evaluate the effectiveness of selected natural organic products,
i.e. poultry manure, organic compost, yeast, and organic
biofertilizers, in controlling the population density of nematodes,
in comparison with Counter 15G (Terbufos), as one of the most
commonly conventional nematicides used.
Evaluate the effectiveness of several mixtures of selected
biocides, with different organic materials, in reducing the
population density of root-knot nematodes.
Determine the effects of different treatments on improving the
tuber yield productivity of potatoes.
Determine the effect of different treatments on the activity levels
of catalase and peroxidase enzymes as important antioxidants,
and estimating the nature of the relationship between them.
Herein, we summarize the results of each part of the present study:
1. Survey of Plant-Parasitic Nematode Genera Associated
with Potato Cultivars
In the first part of our study, the data of incidence nematode
population infesting different cultivars of potato showed the presence
of different nematode genera. There were eight nematode genera
associated with potato soils, viz. The root-knot nematode,
Meloidogyne spp. (Meloidogynidae) was considered as the most
widely distributed genera with the four potato cultivars followed by:
root lesion, nematode , Pratylenchus (Pratylenchidae), spiral
nematode, Helicotylenchus, stunt nematodes, Tylenchorhychus
(Tylenchorhynchidae), stubby-root nematodes, Trichodorus
(Trichodoridae), dagger nematode, Xiphinema (Longidoridae),
needle nematodes, Longidorus (Longidoridae), ring nematode,
Criconemoides (Criconematidae).
the most sensitive to be infested by nematodes.
2. Effects of Different Treatments on Root-Knot Nematodes
Infecting Potato under Field Applications
2.1. The Efficacy of selected Formulations of Biological
Pesticides in Management of Root-Knot Nematode
The data showed that most of the selected biocides significantly
reduced the population densities of root-knot nematodes. The
NemaFree treatment reduced the number of nematodes by
84.7% (estimated using the Henderson & Tilton ’formula), followed
by NemaStop (82.6%) and Dipel® (82.2%) compared to the
traditional nematicide used, Counter treatment which reduced
the population density by 91.2%, after one month of treatment.
The effectiveness of these biopesticides in reducing the number of
nematodes extended up to 105 days of treatment, indicating
reduction percentages by 90.2, 75.9, 83.2, 84.1%, respectively.
In general, the overall means of reduction percentages of
nematode juveniles showed that the most effective treatments
were: Nemafree, Dipel®, Nemastop, and Counter, where reduction
(%) ranged from 89.5 to 85.1%
2.2. Efficacy of selected organic-Soil Amendments in Nematode
Management
The results showed that application of organic compost resulted in
a significant effect in reducing the population density of nematode
after one month of treatment by 54.5%, followed by Nitrobein
(25.8%), Phosphorin (22.3%), Potassium silicate (22.5%).
The overall means of reduction percentages of nematode
juveniles along the period of experiment showed that the most
effective treatments were: Compost (66.3%) followed by Poultry
manure (47.1%) and Phosphorin (45.2%).
2.3. Effectiveness of Treatment with selected Biopesticides in
Combinations with Organic-Soil Amendments
The treatment of tested biopesticides in combination with organicor
biofertilizers showed significant increase in the effectiveness of
these components when applied alone. For example, the results
showed that the best mixture proposed was: [Compost +
NemaStop+ Dipel®], which reduced the population density of
nematodes by 94.4% after one month of treatment, followed by
mixtures: [Poultry manure+ NemaStop + Dipel®] and [Poultry
manure+ NemaStop] with reduction percentages by 93.6% and
90.6%. respectively.
It is worth noting that the effectiveness of these mixtures extended
until the 105-day of treatment, causing a decrease in the number
of nematode juveniles by 95.3, 90.6, 92.4%, respectively.
The overall means of reduction percentages of nematode
juveniles along the whole period of experiment showed that the
most effective treatments were mixtures of: Compost+Nemastop+
Dipel® (96.05%), Poultry manure+ Nemastop+ Dipel® (93.8%),
Poultry manure+ Nemastop (93.8%) and Potassium silicate +
Nemastop (92.9%).
3. Effects of Treatments on Potato Productivity
The results of treatment with tested biological pesticides showed
an overall increase in the average plant productivity of tubers
weight, as compared with that in the untreated control.
Mycorrhizeen® significantly increased the mean total weight of
tubers / plant by 47.8%, followed by Nemafree (41.8%) and
NemaStop (38.7%), in comparison with Counter -treatment which
increased the potato productivity by 45.7% than that of the
control.
The results also showed that the addition of organic products (both
bio-fertilizer and organic compost) led to a significant increase in
the average productivity of the tubers per plant, compared to the
control. Where, soil amendments with either Poultry manure,
Phosphorin®, or Organic compost resulted in an increase in
potato tuber weights by 41.4, 41.1 and 31.2%, respectively. While
the effect of Potassium silicate fertilizer and Nitrobein seemed to
be the least effective, although it increased crop productivity by
19.7% and 20.9%, respectively.
Our results also revealed that soil treatment with selected
biological products in combination with organic- and bio-fertilizes
significantly increased the average plant productivity of tubers by
weight. The most significant mixtures in increasing yield
productivity were the following mixtures, in order:
[Compost+NemaStop] > [Poultry manure+ Nemastop] > [Poultry
manure+ Nemastop+ Dipel®], which increased the average plant
productivity of tubers by weight: 61.6, 53.8 and 51.8%,
respectively.
4. Improvement of Antioxidant Enzymes in Potato by
Application of Biological Pesticides and Organic
Bioactive Products
The levels of enzymatic -antioxidants, Catalase and Peroxidase,
were estimated in potato leaves from different treatments and
compared with these of the control treatment.
The importance of these estimates is due to the vital importance of
both enzymes as antioxidants which they play an important role in
protecting the body’s tissues from oxidative stress caused by the
increase of cracks / free radicals that contain the oxygen element
which may be happened as a result of nematode attack. Therefore,
the results of the chemical evaluation of the activity of these two
enzymes showed the following:
(1) Catalase activity
Our data showed that NemaStop®, NemaFree®, Mycorrhizeen®,
Dipel® resulted in a significant increase in the activity of this
enzyme along the experimental period until the 105- day of the
treatment, compared to the untreated control.
It is worth noting that there is a significant decrease in the level of
activity of this enzyme in plant tissues treated with the traditional
nematicide, Counter .
The addition of Potassium silicate and Poultry manure had also
significantly increased the level of this enzyme.
The integrated effect of adding organic biofertilizers to selected
biocide increased the levels of enzyme activity. The most
significant mixtures were the following mixtures:
Summary
[Nemastop + Nitrobin], [Nemastop + Phosphorin], [Nemastop +
Compost] and [Nemastop + Potassium silicate].
(2) Peroxidase activity
The results showed, in general, that the effects of different
treatments on the levels of Peroxidase were less affected than that
reported on Catalase activity.
For example, treatment with bacterial biocide, Dipel®, resulted in
a slight increase (17%) in the activity of peroxidase than that of the
control.
Similarly, the enzymatic activity was slightly increased after 60
days of soil treatments with tested biofertilizer Phosphorin
(18.4%), Compost (18.8), Nitrobin (17.2%) and Poultry manure
(15.8%) as compared to that of the control.
The addition of organic biofertilizers to selected biopesticide in
mixtures: i.e. [Nemastop+ Phosphorin], [Nemastop + Poultry
manure], [Nemastop + Dipel®+ Compost], resulted in slight
increases (~ 14.3- 17.2%) in enzyme activity levels as compared to
that of the control.
from all aforementioned results, it is concluded that using the
biological pesticides, Dipel®, NemaFree®, and NeemStop®, resulted
in reducing the J2-stage of root-knot nematode in potato fields. The
nematicidal activity of biological pesticides increased if mixed with
some bio-organic fertilizers. The best proposed mixture was:
[Dipel®+ NemaStop + Organic compost], followed by [Dipel®+
Nemastop + Poultry manure], [Nemastop + Poultry manure].
Consequently, the average productivity of tuber yield per plant
increased. The study confirmed the importance of using biological
Summary
biopesticides: Nemastop, Nemafree, Mycorrhizeen, Dipel®,
especially if applied in mixtures with certain organic substances to
increase the activity levels of antioxidant enzymes, Catalase and
Peroxidase, which protect plant tissues from excessive oxidation due
to attacking plants with nematodes.