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Weeds In Late Summer - Are They Worth Chasing?

Orchard weed control was looking good, especially where little rain had fallen to stimulate late weed germination. But where rains have come (even small showers), weed escapes have established under trees. The question now is: Are weed control efforts worth it at this time in the season?

We know from critical period research that only early season weeds will reduce yields. So from a money-return viewpoint, the answer would be NO, Don't bother controlling weeds now as there will not be any more increase in yield.

However, there are other factors to consider:

• Late weed escapes may hamper harvest. This is especially true for early escapes of pigweed and lamb's-quarters, which harden into "trees" and impede pickers. Also, picking up juice apples is much more efficient if weed growth is weak.
• Weed escapes will produce seeds, and may increase weed problems in the future. So for difficult weeds (especially perennials like thistles and quackgrass), it may be worth controlling them now (or preventing seeds).
• Thick weed cover may encourage rodents. Predators like hawks may have more difficulty in hunting rodents where weeds are thick.

Figure 1 - Late weed escapes can have benefits

Have you considered the benefits of late weed escapes? A cover of weedy growth under your trees can have many benefits including:

• Reducing rot in juice apples
• Preventing soil erosion (from both water and wind)
• Encouraging trees to harden off (by absorbing both moisture and nitrogen)
• Providing refuge for beneficial insects
• Adding organic matter to the soil (small quantities, but every bit helps)
• Encouraging soil organisms to flourish, in some cases encouraging herbicide breakdown

As you make your decision on further efforts to manage weeds, make some notes about problem areas for weeds to help you prepare your weed strategy for next season.