Agriculture Reference
In-Depth Information
Crabgrass
This annual,
Digitaria sanguinalis
reproduces by stems rooting at the nodes and seeds. It
usually dies with the first frost. It is tufted, mostly prostrate, and roots at the nodes. The
fruit is a caryopsis. It literally blankets the United States, sparing no geographical area, yet
is limited to environments that are right.
Crabgrass simply says that the soil is low in calcium and that it cannot support decay
starting with actinomycetes molds. It is usually possible to adjust the system in a year or
two, putting a little calcium lime and sulfur or gypsum on the soil in order to restructure the
pH. As this is accomplished, most of the infestation dissipates, virtually rotting away. Usu-
ally applications can be computed on the basis of 1,500 pounds of high calcium lime per
acre, 30-40 pounds of processed and active sulfur per acre. If ammonium sulfate is used, a
little more calcium is required. On certain soils a mixture of calcium lime and gypsum is
also good. As calcium exerts its adjusting capacity to correct the soil, a whole new array of
rotting and decay organisms start eating at the roots of the crabgrass. Desirable humic acids
are made available to release soil nutrients for lawn grasses. These can now begin to fill in
eroded patches formerly occupied by crabgrass.
Digitaria ischaemum
, sometimes called
smooth crabgrass, and
Digitaria filiformis
are somewhat similar, albeit with shorter and
narrower fingers.
