Vol. 15—1961 - NorthEastern Weed Science Society

second application be made not later than 30 days after emergence
of the spinach. The application should be made on clean cultivated
soll.
It is becoming increasingly obvious that with good broad-spectrum
pre-emergence selectiVity, long residual activity has to be sacrificed.
This is also the case for vegetable fields that are
cropped more than once per season. With this in mind, more emphasis
has been placed on a repeat application basis to give
season-long weed control. The concept of multiple applications is
not new. In previous years such use was hampered by various degrees
of toxicity to the foliage. This resulted in only mediocre
weed control because significant amounts of the herbicide remained
on the foliage and did not reach the soil surface and furthermore
contributed to phytotoxicity. Granular formulations may tend to
improve the performance of post transplant or lay-by treatments
and reduce crop residue problems.
Through the use of Vegadex granules, these problems have been
minimized, and weed control is comparable to pre-emergence applications.
A lay-by application at time of last cultivation on
crops such as tomatoes will also benefit from increased crop competition
to decrease subsequent weed development.
It is highly desirable to apply the Vegadex granules directly to
the freshly cultivated soil. Under these conditions the granules
will lodge among the soil particles in the same pattern as they
are distributed. If the granules are applied to CUltivated soil
which has been compacted by rain, the granules have a tendency
to roll to depressions left by the cultivator and results in an
uneven distribution particUlarly if washing rains follow. Since
freshly cultivated soil usually is mOist, activity of Vegadex is
improved. .
The residual herbicide activity of Vegadex is generally from 4 to
5 weeks. In the case of applications following last cultivation
(lay-by), residual activity 1s longer because the soil is no longer
disturbed, and no new weed seeds are brought to the surface.
It is difficult to outline a specific weed control program for
broad usage based on multiple applications since weed problems
differ and also grower interpretation of his problem varies.
In areas where broadleaves are troublesome, post transplant applications
are most effective. Where summer grasses are serious,
applications at time of last cultivation are equally, if not more
important. ~le acute weed problems~ however) do rl0~ al~ayncoin~iAB