General Information


638 is a special formulation containing 2,4-D acid. It is more effective than 2,4-D amines for controlling hard-to-kill weeds such as field bindweed, Russian knapweed, Canada thistle, leafy spurge, cattails, tules and nutgrass. 638 should be applied when daytime temperatures are lower than 80 to 85 degrees. Spraying when temperatures are higher may cause rapid foliar burn and decrease the product’s effectiveness. Treatment at higher temperatures also increases the possibility of crop injury. INJURY TO CROPS FROM THIS HERBICIDE MAY OCCUR. IF YOU ARE NOT PREPARED TO ACCEPT SOME DEGREE OF CROP INJURY, DO NOT USE THIS PRODUCT. Crop varieties vary in response to 2,4-D and some are easily injured. Apply 638 only to varieties known to be tolerant to 2,4-D. If you are uncertain concerning tolerant varieties or local use situations that may affect crop tolerance to 2,4-D, consult your seed company or state Agricultural Extension Service for advice.


Do not apply product through any type of irrigation system. Do not use in or near a greenhouse.

Limitations, Restrictions, and Exceptions


- Apply not less than 7 days prior to planting soybeans, when weeds are small and actively growing. Use the higher rate on larger weeds and when perennials are present. Some weeds may require repeat treatment for adequate control (See GENERAL WEED LIST and below).

- Beggarticks, common broomweed, knotweed, mallow (venice or little), musk thistle, prickly lettuce, Russian thistle, salsify (western or common), smartweeds (annual species),vervains, Alfalfa, Austrian fieldcress, bindweed (hedge,field, European), Canada thistle, docks, dogbanes, goldenrod, ground ivy, hoary cress, many-flower aster, nettles (including stinging), orange hawkweed, tansy ragwort, vervains, western ironweed, wild garlic, wild onion: These species may require repeat applications and/or use of higher rate recommended on this product label even under ideal conditions for application.

- Pigweeds (Amaranthus spp.): Control of pigweeds in the High Plains area of Texas and Oklahoma may not be satisfactory with this product.

- In addition to those weeds found on the GENERAL WEED LIST, 638 will suppress or control the following broadleaf weeds frequently encountered in reduced tillage soybean production systems: bullnettle, smallflowered bittercress, Carolina geranium, smallflowered buttercup, common and rough cinquefoil, red clover (partially controlled), horseweed or marestail, mousetail, wild mustard, field pennycress, cutleaf evening primrose, common purslane, speedwell and Virginia copperleaf.

- Apply no more than 2-2/3 pints in one season prior to planting soybeans. After applying, plant soybean seed as deep as practical or at least 1-1/2 to 2 inches deep. Adjust the planter press wheel, if necessary, to ensure that planted seed is completely covered.

- If desired, 638 may be applied preplant to soybeans in tank mixtures with other herbicides such as Poast, Poast Plus, Gly Star Original or Roundup, Roundup D-Pak, Honcho, Gramoxone Extra, Prowl, Pursuit Plus, Scepter, Scepter 70 DG, Squadron and others that are registered for preplant soybean use.

NOTE: Unacceptable injury to soybeans planted in fields previously treated may occur. Whether or not soybean injury occurs, and the extent of injury will depend on weather and agronomic factors such as the amount of weed vegetation and previous crop residue present that may be in effect between the time of application and the emergence of the soybean plant.

Restrictions and limitations for use on soybeans (preplant):

- Do not apply prior to planting soybeans if you are not prepared to accept the results of soybean injury including possible loss of stand and yield.

- Do not apply when weather conditions such as temperature, air inversions, or wind favor drift from treated areas to susceptible plants.

- Apply no more than 2-2/3 pints per acre in one season prior to planting soybeans.

- Do not mow or cultivate weeds prior to treating with this product as poor control may result.

- Do not feed treated hay, forage, or fodder or graze treated soybeans to livestock.

- Only one application of this product may be made prior to planting soybeans per growing season.

- Do not feed or graze treated cover crops to livestock.

- Do not replant fields treated with this product in the same growing season with crops other than those labeled for 2,4-D preplant use.

Restricted Entry Interval

48 hours