Abstract

Strawberry is an important small fruit crop grown throughout the world due to its rich sources of vitamins and abundance of antioxidants. The US is the world's leading producer of strawberries followed by Mexico. The main strawberry producing states are California followed by Florida, which produce >90% of the strawberries grown in the US. Strawberry production is often threatened by a host of arthropod pests that include insect and mite species. In order for the US to maintain its lead in strawberry production it is vital to develop effective management tools for key insect pests, diseases, and weeds. Some of the major arthropod pests that affect strawberry production include twospotted spider mites,Tetranychus urticae Koch, thrips, Frankliniella and Scirtothrips spp., armyworms, root-boring pests, and many different hemipterans that cause injury to the strawberry leaf and fruit including the tarnished plant bug, Lygus Hesperus, and the seed bug Neopamera bilobata Say. This chapter will summarize some of the key pests that can severely impact strawberry production. We have included some integrated management guidelines to curtail pest's activities during a production season.

Keywords: arthropods, biological control, integrated pest management, monitoring, strawberry

### 1. Introduction

Strawberry is an important crop is the United States with production in 2017 valued at \$3.5 billion USD [1]. Fresh market strawberries dominate this production with a \$3.3 billion USD value. California is the largest producer of strawberries in the United states with 15,459 hectares planted to strawberries in 2017. Florida is the second largest producer with 4330 hectares. The remaining 2000 hectares is spread among Michigan, New York, North Carolina, Ohio, Oregon, Pennsylvania, Washington, and Wisconsin. Pest management is a crucial part of strawberry production especially when even cosmetic injury can make fresh fruit unmarketable.

There are a number of insect and mite pests that can have detrimental effects on strawberry production. Some pests, such as the twospotted spider mite,Tetranychus urticae Koch, are major pests wherever strawberry plants are grown. Others are major pests in certain regions or under specific production systems. Becoming familiar with the mites and insects that are likely to cause economic damage in production systems is an important first step in an integrated pest management (IPM) program [2].

Monitoring is a critical component of a successful IPM program [2]. Scouting is the most common monitoring technique used in strawberry production in the United States [3]. Scouting involves examining a sample of strawberry plants from the field or greenhouse for the presence and abundance of pest mites and insects. A sampling plan should be designed to get a good representation of what is happening in the field or greenhouse. There are also monitoring traps available for certain pest insects. Yellow sticky traps, for example, are often used to monitor for aphids and whiteflies in field and greenhouse situations. The information gained from monitoring is used to determine if a treatment action, such as an insecticide application, is warranted.

2.3 Perennial field production

DOI: http://dx.doi.org/10.5772/intechopen.82069

2.4 High and low tunnel systems

the following season, also [3].

3.1 Twospotted spider mite

pers and cutworms.

strawberries.

3. Leaf pests

Figure 1.

103

L. Buss, UF).

The two key pests (twospotted spider mite and spotted wing drosophila) in annual strawberry production are also key pests in perennial production systems. There are also several beetles that can be major pests in perennial strawberries, which are not present in annual systems. Other potential pests, in addition to those listed under annual field production, include potato leafhop-

Management of Strawberry Insect and Mite Pests in Greenhouse and Field Crops

The pest complex in a high or low tunnel system will be similar to the pest complex in field grown strawberries in the same region. The warmer temperatures in the tunnels may lead to increased pest outbreaks in tunnels compared with field

Leaf pests can be divided into two main groups, sucking pests and chewing pests. Sucking pests include twospotted spider mites, cyclamen mites, chili thrips, aphids, whiteflies, potato leaf hoppers, and spittlebugs. Chewing pests include armyworms, cutworms, and strawberry leafrollers. Injury to leaves reduces the plants ability to photosynthesize (make food), which can reduce the quality and quantity of fruit produced. In perennial production, this injury can affect the yield

Twospotted spider mites,Tetranychus urticae Koch (Figure 1) are oval shaped and tiny. The adults are 0.5 mm in length, which is about the size of a period in 12 point font. They are usually light greenish-yellow in color with two large, dark spots on their abdomens. However, brown, red, orange, and darker green forms also occur. The eggs are spherical and clear to tan in color. The eggs and all stages of mites are usually found on the undersides of leaves. The twospotted spider mite life

deutonymph, and adult. Each of the three intermediate stages feeds and grows for

Twospotted spider mites and eggs on the underside of a strawberry leaf as seen under a microscope (photo credit:

cycle progresses through five stages: egg, six-legged larvae, protonymph,

Action thresholds are needed to determine when a treatment is warranted [2]. An action threshold is the point where the cost of control is less than the economic damage that will result if the pest is left untreated. These vary depending on the pest, region, production system, etc. Numbers of natural enemies present in the field or greenhouse should also be considered when deciding if a treatment action is necessary. The action threshold for releasing biological control agents, such as predatory mites, will be different than the action threshold for an insecticide or miticide application.

Strawberries can be produced in the open field and in greenhouse settings. In the United States, there are two major field production systems for strawberry production [3]. In warmer, southern areas, such as Florida and southern California, strawberries are grown as an annual crop on raised beds covered with plastic mulch. The production season is lengthy (October through March in Florida with berries harvested December through March). In contrast, strawberries are grown as a perennial crop in northern areas of the United States. Matted rows are used and the harvest season is short, occurring during the summer months. Recently, researchers and growers have been experimenting with using high and low tunnel systems. These systems use tunnels to extend the growing season in colder areas. The pest complex in each system (tunnel, greenhouse and field) overlaps but is usually different.

This chapter will discuss the pest complex of each production system. Descriptions of pests, the injury they cause, and management strategies will be presented. Management strategies will include monitoring methods, action thresholds, and treatment options.

### 2. Pest complexes of strawberry production systems in the United States

#### 2.1 Greenhouse production

A well-constructed and maintained greenhouse can prevent larger insects, like moths, from accessing the plants inside. For this reason, the major pests of greenhouse grown strawberries are the twospotted spider mite, aphids, whiteflies, and thrips. Other strawberry pests can, however, be introduced into the greenhouse on infested transplants and equipment.

#### 2.2 Annual field production

Key pests in annual strawberry production throughout its range include the twospotted spider mite and spotted wing drosophila (SWD), Drosophila suzukii Matsumura. Other potential pests include cyclamen mites, aphids, whiteflies, spittlebugs, flower thrips, chili thrips, armyworms and related Noctuid caterpillars, strawberry leafrollers, tarnished plant bugs, strawberry seed bugs, and sap beetles. Management of Strawberry Insect and Mite Pests in Greenhouse and Field Crops DOI: http://dx.doi.org/10.5772/intechopen.82069
