Weed Seeds- The Source of all Problems
The primary reason for controlling weeds during crop production is to prevent crop yield losses due to competition with weeds. However, the majority of Iowa farmers strive to obtain higher levels of weed control than necessary to protect crop yields. The rationale for this contradiction is the concern about the production of seeds by weeds left in the field. Since the majority of weeds found in Iowa row crops are summer annuals, the seed bank is the source of new weed infestations each spring. The seedbank influences both the weed populations that occur in a field and the success of weed management programs. The weed seed cycle is depicted in Figure 1. The size of the seedbank fluctuates widely depending on the magnitude of seed introductions and seed losses. Weeds are legendary for their capacity to produce seeds and for the longevity of these seeds in the soil. While there is no doubt that weeds can be quite remarkable in these aspects, the capabilities of weeds are often exaggerated. This paper will discuss the different components of the weed seed cycle and the importance of the seed bank to weed management.