Agricultural nutrient runoff to the Chesapeake Bay has been under intense scrutiny for more than a decade in Maryland. One method for capturing these nutrients, especially N, is the use of winter cover crops. This study compared various broadcast cover crop treatments with and without soil incorporation to planting winter cover crop seed with a no‐till drill. Seedling emergence and N uptake were the dependent variables measured for two planting dates and seven planting methods. The effects of planting date and planting method for winter wheat (Triticum aestivum L.) and cereal rye (Secale cereale L.) following corn (Zea mays L.) harvest were investigated at two locations. The study was conducted over two winter cover crop growing seasons: 2007–2008 and 2008–2009. Treatments that incorporated the seed into the soil consistently established better stands of cover crops and took up more N regardless of fluctuations in temperature, rainfall, and planting date. Early planted cover crops consistently took up more N than those planted on the later planting date. Performance of the broadcast treatments was highly dependent on rainfall and mild temperatures for success, but did take up notable amounts of N when planted early under good growing conditions. The few differences that were found in the N uptake between wheat and rye within the same planting treatment always indicated that the rye achieved better N uptake than wheat.

Core Ideas Rate of soil P drawdown is a slow process having economic impacts to producers. Cropping system affected drawdown of soil P concentrations at all locations. Forage cropping systems exhibited faster soil P drawdown. Lower initial soil P status resulted in faster soil P drawdown at one location. Soils could take 18 to 44 yr to return to agronomic optimum P concentrations. Phytoremediation remains the only management option to lower soil P concentrations. Elevated soil P concentrations exist where manure has been repeatedly applied over a long period of time leading to regulatory restrictions on P applications targeted to decrease P loss from fields. Phytoextraction uses growing crops to remove contaminants, including P, from the soil through removal of crop biomass. A long‐term study initiated in 1994 compared effectiveness of forage and grain rotations common in the mid‐Atlantic region at reducing soil P concentrations in the absence of additional P application. Five soil P concentrations were established in replicated plots at three Maryland locations through application of manure. Grain and forage plots were established as main plots and soil P concentrations were split plots. Mehlich‐3 extractable phosphorus (M3P) concentrations were measured biennially or annually and rate of soil P drawdown was calculated as a first‐order decay equation. Phosphorus concentration was measured in grain and aboveground biomass from grain and forage plots, respectively, to measure crop P removal. Forage plots had greater P removal than grain plots at all locations studied. Forage plots tended to have greater rate of soil P drawdown at all three locations. An average of 20 yr was estimated for forage plots to return to optimum soil P concentrations, about 100 mg kg−1 Mehlich‐3 P, while an average of 25 yr was estimated for grain plots to return to optimum. Future research should investigate the relative proportions of soil P fractions, as Mehlich‐3 P concentrations may not be completely describing soil P drawdown behavior in the absence of P additions.

unpublished data, 1990) indicate that annual ECB infestations average 0.37 larvae plant Ϫ1 for first generation The European corn borer [Ostrinia nubilalis (Hü bner)] is an impopulations and 1.56 larvae plant Ϫ1 for second generaportant pest of field corn (Zea mays L.) in the northeastern USA. One option for reducing yield loss from European corn borer (ECB) tion populations. Provided that similar infestations ocis the use of transgenic corn hybrids containing a modified Bacillus cur in the Northeast, this would have resulted in an thuringensis (Bt) gene. This study evaluated Bt hybrids, their near estimated annual loss of $35 million due to ECB for isolines, and leading non-Bt hybrids for grain yield, moisture, and Northeast corn producers in 2001. test weight under natural infestations of ECB in 2000, 2001, and 2002 Transgenic Bt corn hybrids were introduced in 1996 at four to six locations across Pennsylvania and Maryland each year. and effectively control ECB and eliminate yield losses Averaged over all locations and years, Bt, isoline, and lead hybrids when subjected to economic ECB infestations. The cost yielded 9.1, 8.6, and 8.5 Mg ha Ϫ1 , respectively. Grain moisture content effectiveness of these hybrids in the Northeast is uncerat harvest was 224, 216, and 214 g kg Ϫ1 and test weight was 705, 713, tain, however. The added cost of Bt hybrid corn seed and 713 kg m Ϫ3 for Bt, isoline, and lead hybrids, respectively. Overall, may be justified in areas with a high probability forBt hybrids produced higher yields, but also had higher grain moisture content at harvest and lower test weight than isoline and lead hybrids. Hyde et al., 1999aHyde et al., , 2003 and higher Yield and moisture content differences were correlated with ECB levels of damage per larva. Better information on ECB infestations, but test weight was not. Isoline and lead hybrid yields infestations and yield and quality of Bt corn grown in the were reduced by 2.37 and 2.60% respectively, for each ECB tunnel. ECB infestation (Northeast would help producers make more informed Precipitation had no consistent effect on Bt and non-Bt hybrid differdecisions when selecting hybrids for corn production. ences for yield, moisture, or test weight. Delayed planting dates were Singer et al. (2000) conducted a 4-yr study in New associated with higher ECB infestations. This may be beneficial in Jersey comparing ECB damage associated with manure predicting sites that could benefit from Bt hybrids. In some environor N fertilizer applications and found Bt corn hybrids ments in Pennsylvania and Maryland, Bt hybrids can result in signifiyielded 8 to 18% greater than non-Bt hybrids in the cant yield advantages.manure treatments, however only 2 to 6% greater in the fertilizer treatments (Singer et al., 2000). Cox and Cherney (2001) concluded that Bt hybrids did not yield to be similar for Bt and isoline hybrids under relatively

Soybean [Glycine max (L.) Merrill] yield losses as a result of plant diseases were estimated by university and government plant pathologists in 29 soybean-producing states in the United States and in Ontario, Canada, from 2015 through 2019. In general, the estimated losses that resulted from each of 28 plant diseases or pathogens varied by state or province as well as year. Soybean cyst nematode (SCN) (Heterodera glycines Ichinohe) caused more than twice as much loss than any other disease during the survey period. Seedling diseases (caused by various pathogens), Sclerotinia stem rot (white mold) (caused by Sclerotinia sclerotiorum [Lib.] de Bary), and sudden death syndrome (caused by Fusarium virguliforme O'Donnell & T. Aoki) caused the next greatest yield losses, in descending order. Following SCN, the most damaging diseases in the northern U.S. and Ontario differed from those in the southern U.S. The estimated mean economic loss from all soybean diseases, averaged across the U.S. and Ontario, Canada was $45 U.S. dollars per acre ($111 per hectare). The outcome from the current survey will provide pertinent information regarding the important soybean diseases and their overall severity in the soybean crop and help guide future research and Extension efforts on managing soybean diseases.

Agricultural nutrient management is an issue due to P loss from fields and water quality degradation. This is especially true in watersheds where a history of P application in excess of crop needs has resulted in elevated soil P (legacy P). As practices and policy are implemented in such watersheds to reduce P loss, information is needed on time required to draw down soil P and how much P loss can be reduced by drawdown. We used the Annual P Loss Estimator (APLE) model to simulate soil P drawdown in Maryland, and to estimate P loss at a statewide scale associated with different combinations of soil P and P transport. Simulated APLE soil P drawdown compared well with measured rates from three field sites, showing that APLE can reliably simulate P dynamics for Maryland soils. Statewide APLE simulations of average annual P loss from cropland (0.84 kg ha) also compared well with estimates from the Chesapeake Bay Model (0.87 kg ha). The APLE results suggest that it is realistic to expect that a concerted effort to reduce high P soils throughout the state can reduce P loss to the Chesapeake Bay by 40%. However, P loss reduction would be achieved gradually over several decades, since soil P drawdown is very slow. Combining soil P drawdown with aggressive conservation efforts to reduce P transport in erosion could achieve a 62% reduction in state-level P loss. This 62% reduction could be considered a maximum amount possible that is still compatible with modern agriculture.