We know the evolution of resistance in waterhemp populations happens faster than new herbicides are discovered, so the recent report of dicamba resistant waterhemp in Iowa by Bayer was not unexpected. Corteva has now reported the discovery of a suspected 2,4-D resistant waterhemp population in Iowa.
Integrated Crop Management News
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Iowa State Extension recently released a newly updated list of soybean varieties that are resistant to the soybean cyst nematode (SCN). The publication contains information on 87 varieties with SCN resistance from the breeding line Peking. Varieties with Peking resistance often will provide greater control of SCN and higher yields in SCN-infested fields that have had varieties with PI 88788 SCN grown for decades. This article contains tables that provide a quick look at the brands, names, and relative maturities of the Peking varieties.
Each year, Iowa State University prepares a list of soybean varieties available in Iowa that are resistant to the soybean cyst nematode (SCN). The list was updated in October 2023 and the publication is now available online. There are 48 more varieties in the 2023 list than in 2022 including 40 more with Peking SCN resistance. Varieties with Peking resistance are highly useful for managing SCN because they limit reproduction of most Iowa SCN populations and protect against yield loss more effectively than varieties with the common PI 88788 resistance.
The soybean cyst nematode (SCN) is estimated to cost soybean producers $1.5 billion annually in North America. A new online resource called the SCN Profit Checker, from the SCN Coalition, uses data collected from Iowa State University research to estimate percent yield loss from SCN and the cost of yield reductions in dollars lost in individual farmer fields. This article explains more about this resource, where to access it and how to use it.
The soybean cyst nematode (SCN) is the most damaging pathogen of soybeans in Iowa and the entire US, costing producers $1.5 billion annually. The pathogen warrants more attention and effort to detect and manage than often is given. It is easily detected and quantified from soil samples. An optimum time to collect soil samples from fields is immediately after corn and soybean harvest are complete. This article explains why and how to collect and submit soil samples for SCN testing.
Harvest has taken off in recent weeks as crops are quickly drying down. The open fields are tempting manure applicators to get started on their manure applications; however, it is worthwhile to pause and consider the fertilizer value that is given up when manure is applied to warm soils.
What is the value and cost of manure?
With yet another sighting of Asian copperleaf (Acalypha australis) this fall, it’s a good reminder to keep an eye out for this new species during harvest. Asian copperleaf (Acalypha australis) was first discovered in Iowa in 2016 in a corn field near Cedar Falls. Prior to this discovery, the only documented infestation in North America was within New York City. Since the initial discovery, it has been found in four other locations, totaling five counties across north central Iowa (Figure 1).
Across Iowa, grain harvest is ramping up. A challenge this harvest season will be dealing with variable grain moistures from field to field as well as within individual fields. Additionally, drought conditions that have persisted all year and rapid accumulation of growing degree days are leading to grain that quickly became overly dry. Follow the below set of tips to limit yield loss this fall.
Decisions for phosphorus (P) and potassium (K) fertilization should consider slightly lower but still fluctuating crop and fertilizer prices compared with last year and very variable rainfall across the state. The current or expected crop and fertilizer prices after harvest and the yield level this harvest have a major impact on producers' fertilization decisions.
Soil-test P and K interpretations were updated last winter
While the registration of 2,4-D and dicamba products for over-the-top use in resistant-varieties has improved waterhemp control for many farmers, weed scientists warned that these herbicides would eventually select for resistant waterhemp populations. Bayer recently reported the discovery of two likely dicamba-resistant waterhemp populations in Iowa, which warrants a discussion on best management practices to slow the evolution of resistant waterhemp populations.