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Planting date and seeding rate affect the microclimate within a crop field. They can influence lepidopteran insect infestation and fungal infections and are an important part of crop management strategy. Altering planting date and seeding rate can also influence yield and quality of silage corn (Zea mays L.). Field research was conducted to identify optimum planting time and seeding rate to minimize insect feeding, ear rot infections, and mycotoxin accumulation in silage corn without compromising yield and quality. Replicated field trials were conducted across multiple site‐years in Michigan with three planting dates (early: April 25–May 10; mid: May 11–25; and late: May 26–June 10) and/or four seeding rates (ranging from 69,160 to 113,620 seeds ha−1, in increments of 14,800 seeds ha−1). Mid‐planting yielded 12%–15% less forage than early and late plantings, partly due to greater insect feeding injury and fungal infections observed in the former. Neutral detergent fiber digestibility, starch, and crude protein concentration were greatest for early planting. Greater predicted milk per hectare and milk per megagram for early planting also indicated superior silage quality. Increasing seeding rate increased insect feeding and ear rot injury only when severity was >5% and >15%, respectively. The impact of increasing seeding rate on dry forage yield was specific to each site‐year. Overall, results showed that early planting of silage corn helps to escape insect and disease pressure and provides better yield and quality, while seeding rate response is variable and dependent on the field environment. Core Ideas: Escaping insect feeding and ear rots by altering the planting date is critical to protect yield and forage quality.Delaying silage corn planting reduced forage neutral detergent fiber digestibility.Insect feeding severity and ear rot increased at high seeding rates (≥98,800 seeds ha−1).Higher seeding rates led to reduction in neutral detergent fiber digestibility and predicted milk yield. [ABSTRACT FROM AUTHOR]

High deoxynivalenol (DON) levels in corn (Zea mays L.) is a grain quality issue for many growers in the US Great Lakes region. High DON levels can be attributed to the interaction of environment, pathogen (Fusarium spp. causing ear rot), and hybrid susceptibility. However, ear‐feeding insects can provide easy access for fungal infection and increase DON accumulation, hence the evaluation of insect protection strategies such as hybrid insecticidal proteins is crucial. Field trials were conducted at four locations in Michigan to study the impact of hybrids insect protection trait on ear injury, ear rot infection, and DON levels. Fungicide application (prothioconazole at silking stage) was conducted at two locations and included non‐treated control. Insect feeding incidence (IFI) and ear rot incidence (ERI) were correlated at three locations but were stronger at locations with environments not conducive to fungal growth soon after silking. Correlation between IFI and DON was observed only at locations with highest insect pressure. Hybrid with Vip3A protein reduced IFI by >70% at all locations but lowered DON concentration at one out of three tested locations compared to non‐Vip3A hybrids. Fungicide application reduced ear rot severity at one of two locations but did not impact ERI or DON levels. Overall, results showed that ear‐feeding by insects can lead to an increase in ear rot and DON levels, and use of hybrids with Vip3A protein can reduce DON levels especially under high insect pressure. Core Ideas: Ear‐feeding by insects can lead to ear rot infection and deoxynivalenol (DON) accumulation in corn grain.Use of effective insect protection trait in hybrid selection reduced ear injury by >70% and can lower DON levels.Fungicide application reduced ear rot at one location but did not impact DON levels at both study locations.Optimal DON management strategies might vary based on field‐specific environmental conditions. [ABSTRACT FROM AUTHOR]

In a previous study, two soybean [Glycine max (L.) Merr.] plant introductions (Pls), PI 567541B and PI 567598B, were found to possess anti-biosis-type resistance to the soybean aphid (Aphis glycines Matsumura). Plants with anti-biosis resistance negatively interfere with the reproduction of the aphid and thus control the insect effectively. Field studies were conducted to determine the inheritance of antibiosis resistance in PI 567541B and PI 567598B. The two resistant PIs were crossed with one or two susceptible soybean lines and the [F.sub.1] and [F.sub.2] plants and [F.sub.2:3] families were evaluated for aphid resistance. All [F.sub.1] plants were found to be susceptible to soybean aphids. The plants in seven [F.sub.2] populations segregated in a 15:1 susceptible/ resistant ratio, which is the expected ratio for a trait controlled by two recessive genes. The [F.sub.2:3] families also segregated in a 15:1 susceptible/resistant ratio. Therefore, the segregation data suggest that two major recessive genes are involved in the resistance in PI 567541B and PI 567598B. This information will be useful to breeders for designing efficient breeding schemes for developing soybean cultivars with antibiosis resistance to aphids.

Since 2000, the soybean aphid (Aphis glycines Matsumura) has become a major pest of soybean [Glycine max (L.) Merr.] in North America. In the USA, there are currently no commercial soybean cultivars with aphid resistance and there are no reported resistance sources in early maturing soybean germplasm. The objectives of this study were to identify sources and types of resistance to soybean aphid from early maturing soybean germplasm. Over a 2-yr period, 2147 soybean accessions from maturity group (MG) 0 to III, originally from northern China, were evaluated for aphid resistance in a greenhouse and in field cages. The plants were hand-inoculated and aphid populations were evaluated 10 d after inoculation. A damage index (0-100%) was calculated for each accession. After 2 yr of evaluation and confirmation in choice tests, four MG III accessions from Shandong province, PI 567543C, PI 567597C, PI 567541B, and PI 567598B, were found to be resistant to the soybean aphid. Two of these accessions, PI 567541B and PI 567598B, possessed antibiosis resistance, preventing the aphids from reproducing on the plants in a no-choice study. PI 567543C and PI 567597C possessed antixenosis resistance. These resistant sources can be used to develop commercial cultivars with aphid resistance for the North Central states., SOYBEAN is the leading oilseed crop produced and consumed worldwide (Wilcox, 2004). In the past half century, the USA has been the world's leading producer. In 2003, the USA produced [...]

The fall armyworm, Spodoptera frugiperda (J. E. Smith), is one of the main pests of corn in many areas of the American continent. The reliance on pesticides to control fall armyworm has led to the development of insecticide resistance in many regions. We determined the resistance levels of fall armyworm to insecticides of different modes of action in fall armyworm populations from Puerto Rico and several Mexican states with different insecticide use patterns. Mexican populations that expressed higher resistance ratios (RR50) were: Sonora (20-fold to chlorpyriphos), Oaxaca (19-fold to permethrin), and Sinaloa (10-fold to flubendamide). The Puerto Rico population exhibited a remarkable field-evolved resistance to many pesticides. The RR50 to the insecticides tested were: flubendiamide (500-fold), chlorantraniliprole (160-fold), methomyl (223-fold), thiodicarb (124-fold), permethrin (48-fold), chlorpyriphos (47-fold), zeta-cypermethrin (35-fold), deltamethrin (25-fold), triflumuron (20-fold), spinetoram (14-fold). Spinosad (eightfold), emamectin benzoate and abamectin (sevenfold) displayed lower resistance ratio. However, these compounds are still effective to manage fall armyworm resistance in Puerto Rico. Fall armyworm populations from Mexico show different levels of susceptibility, which may reflect the heterogeneity of the pest control patterns in this country. The status of insecticide resistance in the fall armyworm from Puerto Rico indicates a challenging situation for the control of this pest with these insecticides in the close future. Lessons learned from this research might be applied in regions with recent invasions of fall armyworm in Africa. [ABSTRACT FROM AUTHOR]