Insect Assessment:

• Thrips: The abundance of winter grains may have lead to thrips being more widespread, but the primary problem was the lack of development of the plants. The cool, damp weather has favored the thrips and cotton development hasn't kept ahead of thrips feeding. This situation should be alleviated once cotton begins to develop under more normal temperatures.
  
• Lygus: Expect moderate to severe migrations, depending on location. In Kern and Kings Counties, tarweed and gumweed are abundant across a wide area in the southern San Joaquin Valley and Lygus populations will complete at least one more generation. Migration could occur near the end of June or later, depending on how quickly the plants die back. Buildup in safflower, tomatoes, alfalfa, and other crops is not expected to be extraordinary based on a lack of useable heat units.
  
• Spider mites: Populations are not exceptional this year but have much less foliage to infest. Damage by thrips and a general growth delay may give the appearance that spider mites are worse than last year.
  
• Aphids: Early season aphid pressure has been light. One management key will be the avoidance of broad-spectrum insecticides early in the season, especially pyrethroids. See Lygus discussion for suggested materials.

Lygus Management Approaches:

• Wherever possible, avoid early and widespread applications of broad-spectrum insecticides since these will exacerbate spider mites, worms, and especially aphids.
  
• Developing and protecting the early crop is essential but caution is advised to avoid over reactions to earliest square set. We can expect fruiting branch to be at 6 or 7 MSN. Retention of first position squares of the first two fruiting branches is not as good as later branches.
  
• The critical level for pest control for Lygus is 73% retention. To expect a plant to hold more than 75% in delayed planting and growth circumstances is unrealistic.
  
• The presence of the pest is a mandatory requirement to trigger topical pest control. In l 995, low early retention lead to widespread applications of pyrethroids even though the density levels may not have required it. The presence of Lygus damage can be ascertained by splitting squares and identifying Lygus feeding. This is not difficult and the benefit of the right decision outweighs the cost of finding the answer. If treatment of low Lygus populations is ascertained, use insecticides that are least likely to cause aphid upsets.
  
• Choose the appropriate insecticide for the level of Lygus threat being faced.
  • A low-density population of Lygus should be treated with insecticides that do not aggravate aphids or spider mites, for example Provado or Monitor.
  • For areas where moderate populations are anticipated, use of Temik side-dressed is a good choice.
  • Where large migrations are occurring, a product like Vydate has good knock-down with reasonable residual.
  • Pyrethroids such as Capture and Baythroid are excellent for Lygus control but should be reserved for moderate to heavy migrations and as late in the season as acceptable.
  • Details of Lygus management are provided in Insecticide Resistance Management Guidelines in San Joaquin Valley and Pest Management Guidelines for Cotton.

Regional Management Opportunities

• Regional approaches through the management of surrounding crops are encouraged wherever possible.
  
• Surrounding crops should be monitored closely to catch Lygus migrations as quickly as possible. Use a sweep net to sample mustards, tarweed, and gumweed.
• Management of alfalfa is a key element in limiting the amount of Lygus migration. Avoid wholesale cutting of blocks but checkerboard an area with various stages of alfalfa growth. This will provide preferred habitat of alfalfa rather than cotton for Lygus. Leave uncut strips through the field whenever possible.

Summary Statements

Management of Lygus must take into account the impact of insecticide decisions on other arthropods. When growth and development is delayed, growers become anxious about early season square set. Care must be exercised to avoid unnecessary broad-spectrum insecticides that are both costly and disruptive. The yield potential for the 1998 crop has already been affected. Placing unrealistic retention demands on the plant and PCAs will only lead to more problems. Final advice would be:

• watch the crop development closely
• watch Lygus populations in surrounding crops and weeds; be prepared for their migration
• inspect the fields frequently; twice or even three times/week
• if any doubt on the source of square loss, split squares and look for Lygus damage
• trigger insecticide applications on real problems
• use the appropriate insecticide for the situation