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GREEN HOUSES

Nutrient deficiencies frequently oc-
cur when soil-based nutrients are plant
unavailable having become ‘locked
up’ through interactions with other ele-
ments, often caused by prevailing soil
pH (acidity/alkalinity) with zinc a case in
point. Uptake of moderately mobile zinc
ions is generally inhibited by alkaline
soil conditions and specifically by soil
phosphate interacting with zinc to form
insoluble zinc phosphate. Similarly iron
may be present in soils in considerable
quantities but unavailable to growing
Greenhouse-grown lettuce will provide Growers who follow a well-structured plants due to high soil pH which gen-
a crop in as little as 3 to 4 weeks programme of foliar feeding can erally prevails in the calcareous soils of
(Picture courtesy Omex) expect superb crops of tomato like Middle Eastern and Mediterranean ba-
sin countries.
the cherry tomato shown here I asked Peter how continued applica-
lishment of strong and secure root sys- (Picture courtesy Omex) tions of Omex Combi (Micromax) could
tems by using Omex Nami (Bio 20) will help in such situations. “Omex Combi
go a long way to counteract the effects ing off disease,” says Peter. DP98 is used (Micromax) has a full complement of
of these microscopic round worms,” says in other countries where it is recognised chelated micronutrients. Routine appli-
Peter. to reduce seedling mortality rates from cation of Omex Combi (Micromax) as a
Another ubiquitous problem for seed- damping off. foliar spray overrides limited plant avail-
lings irrespective of plant species is ability of soil nutrients. Omex Combi
(Micromax) is used on the broadest
fungal-inspired ‘damping off’ disease Omex Combi (Micromax) spectrum of greenhouse crops including
festering on soft, young plant growth in tomato, capsicum peppers, aubergines,
crowded seedbeds and thriving on high feeds fast foliar growth cucurbits, lettuce, brassicas, peas and
humidity and leaf surface wetness. Plants taken out of the nursery bed and beans and grapes,” says Peter Prentis.
These soil-borne fungal pathogens transplanted into their final positions are
target and infect plants at different times poised to take off with fast foliar growth
in the seed germination and seedling and fuelled by an ‘unquenchable thirst’
establishment process to cause distinct for nutrients, but thwarted on two counts
pre-emergence and post-emergence relating to the plants’ root status and
phases of damping off. plant availability of nutrients in the soil.
Transplanted seedlings now shorn of
root hairs are in a state of ‘shock’ and
unable to indulge in the unimpeded up-
take of water and nutrients until a new
complement of root hairs is grown. “At Uniform crop growth is one particular
no other time will plants benefit more benefit of foliar feeding under the
from foliar feeding with Omex Combi
(Micromax) offering a complete range controlled environmental conditions of
of essential micronutrients in a chelated the greenhouse, as exemplified by the
form,” says Peter Prentis. cucumber crop shown here
Root hairs have been renewed and (Picture courtesy Omex)
Growers who follow a well-structured rapid plant growth is underway but other Omex Calmax and Omex
problems now related to specific soil nu-
programme of foliar feeding can trient shortfalls may ‘kick in’. “Periods of
expect superb crops of tomato like particularly rapid growth are the times DP98 working in unison
the plum tomato shown here when shortfalls of particular nutrients Omex Calmax and Omex DP98 are
(Picture courtesy Omex) are most likely to occur and show up considered together because this is
as nutrient deficiency symptoms. It is how they are increasingly applied and
worth remembering that the speed and operate on the leaf surface and inside
In the pre-emergence phase seedlings success of overall crop plant growth and
are infected and killed just before they development is dictated by the nutrient the plant. This combination frequently
reach the soil surface. Pre-emergence which is in least supply,” says Peter Pren- comes into action and play during later
damping off is due to the rapid death of tis. stages of the crop cycle to ensure suffi-
the radicle (first root) and the plumule cient calcium for strength and quality
(first shoot) with a complete rotting of of harvested produce. Omex Calmax
seedlings. Post-emergence phase is supplies the calcium while Omex DP98
characterised by infection of the col- provides phosphite ions to ‘carry’ the in-
lar (junction between root and shoot) herently immobile calcium ions into the
at soil surface level. The infected tissue plant.
becomes soft and water soaked and Ensuring crops can access enough
affected seedlings topple over or col- calcium is one of the biggest constraints
lapse, hence the name ‘damping off’. confronting growers even on calcareous
Damping off disease is caused by mul- soils which ironically, as the name sug-
tiple pathogens, including fungus-like gests, are potentially high in calcium.
Phytophthora and Pythium and true fungi ‘Potentially’ is the ‘key’ word here, be-
such as Rhizoctoni and Fusarium. “Omex cause even with high soil calcium levels
Nami (Bio 20) applied during this early Capsicum sweet peppers respond plant roots and vascular systems will
stage generates stronger seedlings with well to foliar feeding under greenhouse face extreme difficulty in accessing, ab-
more robust shoots and stems to help sorbing and delivering calcium because
young plants avoid or overcome damp- cultivation (Picture courtesy Omex) the ion is poorly mobile.

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