The primary purpose of this book is to provide cooperators and contributors a summary of the results of field research. Many data summaries and conclusions in chapters from this book have been submitted to the American Phytopathological Society for publication in Plant Disease Management Reports in 2015.

Nutrient recommendations for most essential elements are based upon soil test calibration studies. These calibration studies relate the likelihood of a profitable plant response to nutrient addition with the nutrient concentration in the soil as measured by a soil test. However, nitrogen (N) is not included in routine soil analysis because it is not possible to test soils in advance of planting and accurately predict the need for N fertilization.

Barley Yellow Dwarf (BYD) is caused by the viral pathogen Barley Yellow Dwarf Virus (BYDV) complex. The BYDV complex consists of five closely related viruses in the Luteoviridae family.

Cercospora leaf blight and purple seed stain are caused by the fungus Cercospora kikuchii. This is a widespread disease, but yield loss is rarely observed.

Cereal Leaf Beetle: Overwintering adults emerge in mid-March and begin to lay eggs after 2 to 3 weeks of feeding. Since females prefer to lay eggs on young plants, spring-planted oats and late-planted wheat are the predominant hosts. 

Charcoal rot of soybean can be a major yield-robber of drought-stressed soybeans in Delaware. The disease is caused by Macrophomina phaseolina, a common soil-borne fungal pathogen that inhabits much of Delaware’s agricultural soils. 

Curvularia leaf spot is caused by the fungal pathogen Curvularia lunata. This disease was first observed in Delaware at the end of the 2020 season. The economic impact of this disease is still unknown in the United States.

Like most plants, corn growth progresses through three main phases: germination, vegetative, and reproductive stages. During germination, seeds break dormancy when soil temperatures exceed 50°F. They absorb (imbibe) water, triggering metabolic processes that lead to emergence and the start of the vegetative stage

Corn smut is caused by the fungal pathogen Ustilago maydis. Spores are spread through wind or water splashing to nearby plants. This pathogen infects the corn through the silks prior to pollination, or by wounds on the plant.

The Dectes stem borer (DSB) is a longhorn beetle that is native to North America, and feeds on many wild and some cultivated plant species. 

Glyphosate is the active ingredient in Roundup, Touchdown, Duramax, and numerous other brand names. If resistance is suspected in one of your fields, some questions should be asked to help determine if herbicide resistance is the reason for lack of control.

Downy mildew of lima bean, caused by the oomycete, Phytophthora phaseoli, is a common disease in Delaware production areas. Proper identification and management of the disease is critical for protecting lima bean yields. This publication will review how to correctly identify the disease, describe its lifecycle, and outline management options for growers.

The end-of-season corn stalk nitrate test is a simple, inexpensive tool that can be used to assess the nitrogen (N) status of a corn crop at the end of the growing season. Studies in Delaware, and other states, have shown that corn producers can use this test to improve their N management programs on a site-specific basis (Binford et al., 1990; Sims et al., 1995). 

Many crop management decisions require farmers or their agronomist, crop consultant, or nutrient consultant to make an estimation of the expected yield from a given field. Farmers recognize that yields for the same crop are variable from field-to-field and that a given crop cannot be expected to produce a consistent yield across the entire state. 

Early Season Symptom Chart: After spring green up. Symptoms not expressed on leaves emerge after the average temperatures reach 68°F +.

Caused by the fungus Cercospora sojina. The occurrence and severity of this disease varies across the region. Resistance to Group 11 (QoI) fungicides has been widely documented.

Over the past 10 years the disease has been reported throughout soybean growing regions of the United States as far north as Minnesota [1].  FLS occurs in Delaware but to date its effects have not been severe.  This publication will discuss symptoms of the disease, the disease cycle, and management recommendations.

FHB, or scab, affects wheat, barley, oats, corn, and other grasses. Fusarium graminearum (syn. Gibberella zeae) is favored by warm, humid conditions during flowering and early kernel development.

Fusarium head blight (FHB) is considered to be one of the most devastating diseases of wheat and barley worldwide. Multiple outbreaks of FHB have affected Delaware growers over the past decade, most recently in 2013. 

Grass Sawfly - Adult sawflies emerge in early April, mate and begin to lay eggs in the leaf margins of small grains. Most egg laying is complete by early May.

Gray leaf spot is caused by the fungal pathogen, Cercosporazeae-maydis. This disease is favored by warm temperatures over 80°F, and extended periods of high humidity. Fungal spores overwinter in corn crop residue, increasing chances for infection on non-rotated crops.

Gray leaf spot, caused by the fungus Cercospora zeae maydis is the most significant yield-limiting disease of corn worldwide [1].  The disease was first reported in Illinois in 1924, and has increased in prevalence throughout corn growing regions since 1988. 

Gather tools that will help you acquire a sample, cutters, small shovel, hand lens, plastic bags, marker, etc. Go to the field with an open mind and investigate all possibilities!

Growers, consultants, and the agribusiness industry often ask if they can benefit from changes in their weed management practices, such as the use of a different herbicide, altering the rate of the existing herbicide, incorporating cover crops, or using a new type of cultivator. Comparing changes on separate farms, or even separating fields into halves, often can lead to erroneous conclusions because of the variations within and between fields.

Pigweed is one of the most wide-spread weed species in Delaware and the region, infesting vegetable crops as well as grain crops. Pigweed is capable of quickly becoming the dominant species in a field due to its high seed output, producing over 100,000 seeds per plant.

Soil acidity, often measured as pH, plays a crucial role in plant health and overall soil productivity. Imagine the soil as a complex ecosystem that provides essential resources for plant growth. Just as humans thrive within a comfortable temperature range, plants have specific pH preferences for optimal development.

Cover crops play an important role in protecting the soil and water when main crops like corn or soybean are not actively growing. The National Conservation Service promoted the use of cover crops during the Dust Bowl crisis of the 1930s, to protect soils from erosion.

The pH scale ranges from 0 to 14; a pH value of 7 is considered neutral, while pH values less than 7 are acidic, and pH values greater than 7 are alkaline. The pH values of soil usually range from pH 4.0 to pH 8.0; higher or lower pH values are very rare and are normally found only in severely disturbed soils or in soils that have been amended with some type of acidic or alkaline material.

When creating maps of field crops, one goal is to estimate plant health or responses to management. To achieve consistent imagery, drone flights must account for lighting conditions. While discussions often focus on avoiding variable cloud cover by flying on clear or overcast days, the sun’s angle also plays a critical role. 

The Delmarva Peninsula stands out as a prominent hub for broiler production, accounting for more than 596 million broilers in 2022 (Delaware Chicken Association, 2023). In 2022, Delaware raised approximately 234 million broilers, with a production value of 1.53 billion U.S. dollars (USDA NASS, 2023).

When observing unexplained stunting, wilting, or death in crops. When planting into a field with a history of nematodes. In areas with prior poor performance.

Unlike other nutrients, such as potassium or phosphorus, the nitrogen (N) requirement of corn cannot normally be met by N found in the soil. Consequently, most of the N needed by corn is supplied by applications of commercial fertilizers or manures unless crop rotations include legumes (e.g., alfalfa, clover, hairy vetch, soybeans), where N available from legume residues can often provide a significant percentage of corn’s N requirement.

Soybean is second most widely produced crop in DE, ranking just behind corn for grain. In 2017, approximately 160,000 acres of soybeans were produced in Delaware with an average yield of 51 bu/ac.

The amount of nitrogen (N) removed by the harvested portion of the crop is needed to develop nutrient balances. However, N removal by crops can vary considerably from field-to-field and year-to-year. 

Northern corn leaf blight (NCLB) is a disease of corn caused by the fungus, Exserohilum turcicum. Severe outbreaks of the disease can cause up to 30-50% yield loss in dent corn if the disease is established before tassel [1]. NCLB also causes significant reduction in quality in sweet corn and silage corn. This publication will outline how to identify the disease, review its lifecycle, as well as appropriate management options for growers.

Crops often receive beneficial nutrients such as phosphorus (P) from manure and/or commercial fertilizer applications. However, the Delaware Nutrient Management Law limits the amount of P that can be applied to many agricultural soils in Delaware. 

Physoderma brown spot is caused by the fungal pathogen Physodermamaydis. Infection occurs in the leaf whorl when water has been present for an extended, warm period. Disease is limited and does not typically cause economic loss in the Mid-Atlantic.

Powdery Mildew (PM) is a fungal leaf disease caused by Blumeria graminis , which can reduce grain yield and quality in cereal crops.

Caused by many species of the oomycete pathogen Pythium. Pythiumspecies are favored by periods of extended soil wetness.

Sweet corn is one of the few crops for which insect pests drive most of the pest management program. A number of caterpillar pests attack sweet corn, infesting ears and rendering the ear and the whole planting unmarketable. In addition, caterpillars will also attack whorl stage sweet corn, and other insect pests can occasionally cause economic damage by themselves to the ears. This document focuses on the primary sweet corn pest, the corn earworm. 

The root-knot nematode (RKN), specifically the southern root-knot nematode (Meloidogyne incognita), is a yield-limiting nematode present in many Delaware fields. It is particularly damaging to soybean and can be a chronic pest if not managed properly. 

Sclerotinia stem blight (SSB) is common on snap and lima beans and appears sporadically in soybeans. SSB is considered a minor disease of soybeans in Delaware but it can cause significant yield loss under the right conditions. This publication will discuss disease identification, disease cycle, and management recommendations for SSB.

The drone market targets many different customers, including agricultural professionals. Drone videos and photography allow for a different perspective of the field and have the potential to uncover in-season production issues that scouting may miss. Assessment of crop fields can be made quickly when flying 200-400 feet above the crop.

Soybean Cyst Nematode (SCN) is the most yield limiting pathogen of soybeans across the US. Often referred to as a “silent yield robber”, SCN may be present and reducing yield without notable aboveground symptoms

Soybean severe stunt virus (SSSV) is a putative neopvirus causing a soilborne disease of soybeans in Delaware first described in 1988.

Stalk rots are one of the most significant set of diseases on corn.  These diseases are insidious, and often growers are unaware of their effects until harvest.  Low levels of stalk rot occur in nearly every corn field in Delaware, and severity and incidence varies from year to year. 

Five major soil insects can be found in corn fields: seed corn maggot, white grubs, wireworms, cutworms and rootworms. Corn rootworm populations have increased in continuous corn production areas of New Castle and northern Kent counties. 

Cost-effective, practical, and environmentally sound best management practices (BMPs) for poultry litter management are needed to reduce nutrient losses to the environment during storage, handling, and land application of poultry litter. These practices help Delaware meet water quality standards and keep poultry growers competitive in national and international markets.

As an emerging technology for farmers, drone terminology may cause confusion. However, the practical use of drones and sensors is fairly straightforward.