Page 19 - 04 Cotton SA October 2014

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practices to manage one or more pests, or in the soil. This product must however of clean planting material can at times be a
although each practice has limitations. be applied exactly as indicated, otherwise hindrance to many small scale growers. Weed
Maximum benefi t is realized when several of it can be phytotoxic to the emerging cotton control is essential as some weeds are also
these practices are employed in an integrated plants. It is known that Vydate® (oxamyl) hosts for the root-knot nematode. Nematodes
management system. Utilization of diff erent also stimulates plant growth in the presence usually are introduced into new areas with
control strategies in a management system is or absence of nematodes as well as being infested soil or plants. Irrigation water from
a good alternative for growing cotton in places an eff ective nematicide as was observed in around infested plants must not be allowed
infested with root-knot nematodes. Integrated results obtained in various nematode trials. to run off , as this also spreads nematodes.
nematode management approaches At trials in the Northern Cape Province it was Nematodes can be present in soil attached
which involve a combination of chemical, found that Vydate® granules reduced the root- to tools and equipment used elsewhere,
biological and cultural methods could more knot nematode numbers with a subsequent therefore thoroughly cleaning of the tools
effi ciently regulate nematode populations. increase in yield. A slight phytotoxic eff ect before using them in your fi eld is essential.
Besides chemicals, other control measures in could be present on the lower leaves of
view of the need to replace highly toxic and the plants. In recent years, nematicide seed Crop rotation is the single most useful practice
potentially polluting chemicals used to control treatments were commercialized with much and is most realistically applied to annual and
plant parasitic nematodes with less dangerous lower health risks compared to aldicarb. short-term perennial crops. Although rotations
chemicals or preferably with biological control AVICTA® (Abamectin) seed treatment can be may not control nematodes completely, they
agents. Cultural practices such as crop rotation, used - however it might only off er early-season can reduce populations suffi ciently so that
inter- and intra-cropping, cover/trap crops, nematode control. non-fumigant nematicides may be adequate.
soil amendments, fallow, time of planting/ Prior to use of crop rotation, the identity of
harvesting, and general farm hygiene are Meloidogyne species should be understood,
especially important for low-value crops, but Biological control methods its host range and also the cropping history
must form part of an integrated nematode of the fi eld evaluated. This is critical in
management system. Over a number of years studies were done decision making to avoid indiscriminate use of
to compare various chemical nematicides, nematicides and also scale down management
bio-nematicides and organic additives alone costs. Dependence on nematicides can be
Chemical control or in combination to decrease or eliminate reduced or eliminated if root-knot nematode
the use of nematicides in the control of
In the recent past, the usage of nematicides nematodes on cotton. None of the biological populations are depressed suffi ciently by
has led to a signifi cant reduction of root knot control agents, that have been evaluated, rotating with non-host crops. Longer rotations
nematodes populations in crop production. performed eff ectively on their own and reduce nematode populations more than
the long-term use of nematicides has led to cannot act as substitutes for aldicarb. Several short rotations. A long rotation of up to three
an underestimated eff ect of Meloidogyne attempts have also been made to use the of or four years between susceptible crops,
species however, with diminishing options Trichoderma species fungi to control plant depending on the nematode species present,
for use of nematicides, Meloidogyne species parasitic nematodes as it has the ability to will give maximum increase in yield. Rotating
problems are steadily beginning to resurface. form mutualistic endophytic relationships nematode suppressive cover crops, such as
Nematicides reduce high populations of with several plant species. Soil amendment sunn hemp (Crotalaria juncea L.) with fi eld
various Meloidogyne species in the soil procedures involving the application of or cash crops may strongly suppress root-
though they do not completely eliminate organic materials such as farm manure knot nematode populations and benefi t the
them particularly once the symptoms have and extracts from marigold to release toxic following crop. However, certain crops, such
started to be noticed. Breaking of large lumps compounds that can kill plant parasitic as sunn hemp, can increase the numbers
of soil, good soil humidity and removing crop nematodes have also been explored as a form of certain lesion nematode species. In the
remains of the previous season from the soil of biological control. To achieve better results selection of rotational crops all the important
is very essential for these nematicides to work from soil amendments, organic materials nematode species that might occur on a
well. Recently, the most effi cient nematicides, should be applied at high rates to have a specifi c crop such as cotton should therefore
including aldicarb (Temik®) have been banned signifi cant eff ect on nematode populations. be considered and identifi ed to species level.
in South Africa due to the toxic characteristics In general, the use of organic material is not The limitation of using crop rotation as a
of their active ingredients. Control of only cheap but also improves the effi ciency of control strategy in commercial farms is
nematodes with aldicarb has been achieved in these antagonistic bacteria by off ering them that it is not economically feasible due to
cotton production for many decades, however ready nutrients which are essential for their economic losses which may be incurred
due to residues in the food chain and the growth and survival. during the fallow periods and also in trying to
misuse of this chemical it has been withdrawn establish a new crop in large scale as the
from the market. The other disadvantages previous one.
of using chemical methods to control the Cultural control methods >>> 21
nematodes are that they are expensive to
small scale farmers. Cultural practices include farm hygiene, crop
rotation, physical methods and use of resistant
Some other products that can be used include crop cultivars. Many of these practices have
Stress Buster®, Crop Guard®, Vydate® and been used successfully to reduce the spread
AVICTA®. Stress Buster® is an Illovo product, of Meloidogyne species in diff erent crop fi elds
which has the potential to lower root-knot for many years.
nematode numbers and could be included
in an integrated nematode management Where there is a serious nematode problem
system. Crop Guard® is a unique emulsifi able the effi cient removal of roots at the end of the
concentrate that has been formulated for the season will help to reduce nematode damage
control of nematodes in the soil. It is said to in subsequent crops. The roots should be
kill harmful nematodes on contact and can exposed and destroyed immediately following
be applied throughout the growing season harvesting to eliminate the breeding sites for
without leaving harmful residue on the plant nematodes. However, the cost and availability

Katoen SA Cotton 19 September 2014