Posts Tagged ‘19:3’

Agronomic Crop Insects – April 8, 2011

Friday, April 8th, 2011

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

Alfalfa
Be sure to watch for an increase in levels of alfalfa weevil and pea aphids. Both can be found in fields at this time. When sampling for aphids and weevils, collect a minimum of 30 random stems throughout a field and place them top first in a white bucket. For aphids, you want to count the number present per plant as well as any that have dislodged from the stem into the bucket. As a general guideline, you should consider a treatment in alfalfa less than 10 inches tall if you find 40-50 aphids per stem. The treatment threshold for alfalfa 10 inches or taller in height is 75- 100 per stem. Although beneficial insects can help to crash aphid populations, cooler temperatures will slow their activity. As a general rule, you need one beneficial insect per every 50-100 aphids to help crash populations. For alfalfa weevil, you will also want to record the number of weevil larvae per stem. The following thresholds, based on the height of the alfalfa, should be used as a guideline when making a treatment decision: up to 11 inches tall – 0.7 per stem; 12 inches tall – 1.0 per stem; 13 – 15 inches tall – 1.5 per stem; 16 inches tall – 2.0 per stem and 17 – 18 inches tall – 2.5 per stem.

Wheat
Low levels of aphids and cereal leaf beetle adults can be found in fields throughout the state. Since we are past the prime time for barley yellow dwarf transmission (fall transmission is the most important), the next important time to consider aphid management in small grains is at grain head emergence. Since cereal leaf beetle populations are often unevenly distributed within the field, it is important to carefully sample fields so that you do not over or under estimate a potential problem. Eggs and small larvae should be sampled by examining 10 tillers from 10 evenly spaced locations in the field while avoiding field edges. This will result in 100 tillers (stems) per field being examined. Eggs and larvae may be found on leaves near the ground so careful examination is critical. You should also check stems at random while walking through a major portion of the field and sampling 100 stems. The treatment threshold is 25 or more eggs and/or small larvae per 100 tillers. If you are using this threshold, it is important that you wait until at least 50% are in the larval stage (i.e. after 50% egg hatch).

Potential New Pest of Fruit – Spotted Wing Drosophila

Friday, April 8th, 2011

Joanne Whalen, Extension IPM Specialist; jwhalen@udel.edu

By now, all should be aware of the newest insect pest present in the Mid-Atlantic Region, the Brown Marmorated Stink Bug. However, there is also a potential for another new pest in 2011, the Spotted Wing Drosophila. These flies can infest and cause a great deal of damage to ripening fruit, as opposed to the overripe and fallen fruit that are infested by most other Drosophila species. Females damage fruit by slicing through the skin with their knife-like ovipositor, and inserting eggs that develop into small white larvae. These cuts can also be a pathway for fungal pathogens, leading to greater reductions in fruit quality. Therefore, knowing that it is in the area and how to monitor it is important to avoid economic loss. This insect is a pest of most berry crops, cherries, grapes and other tree fruits, with a preference for softer-fleshed fruit. In areas where it has been detected, it is has become an important pest of cherries, raspberries, blackberries, blueberries, strawberries, grapes, peaches, and plums. So far it has been detected in California in 2008, in Florida and Oregon in 2009, and in Michigan, North Carolina and South Carolina in 2010. Although we do not have the resources to do an extensive monitoring program, we are currently trapping for it in one location in Delaware in 2011.

For more information on monitoring, identification and control of this insect pest, please check the following links:
http://www.ncipmc.org/alerts/drosophila.cfm
http://swd.hort.oregonstate.edu/

Strawberry Angular Leafspot

Friday, April 8th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

There have been two samples of angular leafspot that have been diagnosed this spring. One sample was from high tunnel production, the other annual strawberry under row covers. As you can see from the picture this bacterial leafspot produces angular watersoaked spots initially (Photo 1) that turn dark and eventually brown with time (Photo 2). The bacteria are limited by the vein pattern in the leaf which gives it the diagnostic angular pattern. This disease can cause leaf loss, and, when conditions are very favorable during fruit set, the calyx can become infected and that can reduce the marketability of the fruit. Wet conditions favor the disease, especially if irrigation is needed for frost protection. The bacteria that cause the spring symptoms come from systemically infected overwintered plants and dead leaves, and from infected transplants. Copper sprays can be effective in limiting spread once it is identified but over-application can be phytotoxic, so be careful. Prevention of angular leafspot in the plant nursery and its dissemination in transplants is crucial to controlling this disease.

Photo 1. Watersoaking symptoms

Photo 2. Angular leafspot symptoms.

Mancozeb Label Updates

Friday, April 8th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Good news on the fungicide front. Tolerances were established for mancozeb to replace some of the uses that maneb was labeled for. Maneb is no longer being manufactured. This has led to the first labels of mancozeb for use on broccoli, peppers, cabbage and leaf and head lettuce. Manzate Pro-Stick from UPI has a supplemental label for these uses, pending state approvals. I am sure the other manufacturers of mancozeb will have labels shortly. See the linked label for details: http://agdev.anr.udel.edu/weeklycropupdate/wp-content/uploads/2011/04/ManazteProStickVegSupplement.pdf. This label expansion was needed especially for control of anthracnose on peppers. These additions are not in the 2011 Commercial Vegetable Recommendations so you need to be aware of that.

Fruit and Vegetable Growers Association of Delaware Hires a Special Programs and Outreach Coordinator

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

The Fruit and Vegetable Growers Association of Delaware has just hired Sara Busker as their Special Programs and Outreach Coordinator. Sara is a University of Delaware graduate and grew up on a dairy farm near Harrington, Delaware. She was very active in 4-H and FFA and has extensive leadership and public presentation experience in those youth organizations. She was a former Delaware Dairy Princess and in that role gain experience planning activities that promoted DE products to farm audiences, consumer groups, and school groups. She also served for 2 years as the Kent County 4-H Summer Day Camp Director working with children ages 5-12 and is currently also a site coordinator for a 4-H After-School program in Dover with an everyday focus on teaching children to eat well. In addition, Sara works part-time for the Delaware Department of Agriculture and is currently working on updating the DE Farm Market Directory.

Sara will be providing support for programs being developed by the Fruit and Vegetable Growers Association of Delaware working directly with board members and university advisors. Sara will help with membership outreach and work to increase membership. She will maintain and update the association website, blog, Facebook, and Twitter pages and assist in publishing an association newsletter. One of Sara’s main jobs will be to coordinate a FVGAD initiative to promote vegetable and fruit consumption in Delaware and promote locally produced vegetables and fruits. She will be promoting vegetable and fruit consumption around the state at public events targeting parents. Sara will also be offering support to direct marketers in Delaware who offer school tours on produce farms with educational programs about vegetables and fruits that are age appropriate.

Sara will also be conducting programs in elementary schools to educate about the importance of eating fruit and vegetables and on what produce is grown in Delaware. She will also provide education based on farm to school programs emphasizing the health benefits of the local produce being supplied to schools and will offer support school garden initiatives with educational programming on the benefits of growing and eating produce. She will also assist with grower workshops on producing for and selling directly to schools, colleges, institutions, and restaurants.

In addition, Sara will be assisting with outreach on produce food safety, Good Agricultural Practices (GAP), and Good Handling Practices (GHP), by working with farmers to develop finished farm food safety plans and prepare for audits. She will set up sessions for food service managers to better understand produce food safety and GAP’s.

Sara will be out and about visiting many DE produce growers in the coming months to learn more about the produce industry and to develop ideas on how to best promote DE grown fruits and vegetables. Please welcome her to your farms and businesses.

Water Testing for Produce Food Safety and Third-Party Audits, DPHS Lab Agrees to Do Testing

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Water testing for microbial indicators is a recommended Good Agricultural Practice (GAP) for irrigation water and Good Handling Practice (GHP) for packing house water and is part of a produce food safety plan. It is a common requirement of third party GAP and GHP audits.

Water testing should be done yearly. For wells used in packing houses, samples should be taken just prior to the packing season. For irrigation wells, samples should be taken at the beginning of the irrigation period. For irrigation using surface water (ponds, streams, rivers, ditches), it is recommended that water be tested at the beginning of the irrigation period and just prior to first harvest.

For all sources, water should be tested for generic E. coli, the indicator bacteria for fecal contamination of water. For irrigation water, test should be done in a way to quantify bacterial levels (numbers of bacteria in the sample).

For packing houses, the water should be potable (same as drinking water) and should have no E. coli.

For irrigation water, current guidelines are that the samples where water will contact the harvested part of the vegetable or fruit should be less than 126 CFU (colony forming units) or MPN (most probable number of bacteria) per a 100 ml sample. For crops where there will be no foliar contact the sample should be less than 576 CFU (or MPN)/100 ml. Sources over these levels should be evaluated for sources of fecal contamination (livestock, wildlife, sewage).

A MOU (memorandum of understanding) is being finalized between the Fruit and Vegetable Growers Association of Delaware and the Delaware Public Health Service Laboratory to do water testing for Delaware produce growers. For wells with potable water where presence or absence of E. coli needs to be tested, the cost will be $2.00 per sample. For irrigation sources where numbers of E. coli need to be determined, the test will be $18.00 per sample. Details of the program are being worked out and the program should be up and running within 4 weeks.

Spring Cover Crops for Vegetable Rotations

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

One principle of managing for improved soil health is that you should always have a crop growing on the soil. This will maintain or add organic matter, provide benefits from the action of growing roots, and recycle nutrients.

Where fall cover crops were not planted due to late harvest, spring cover crops can be planted and provide some benefit where vegetables are not scheduled until late May or June. Cover crop options for early April planting include spring oats, mustards, and annual ryegrass. Plant oats at 90-120 lbs per acre, mustards at 10-20 lbs per acre, and annual ryegrass at 20-30 lbs per acre if drilled. Increase seeding rates by at least 50% if surface broadcast. These cover crops can be no-tilled into soybean or corn stubble.

Managing Windbreaks in Vegetables

Friday, April 8th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Many vegetable growers plant windbreaks between areas where plastic mulch will be laid and vegetables will be transplanted. Windbreaks are often planted between every bed, every 2 or 3 beds, or in drive rows between groups of beds (4-8 beds). Windbreaks protect young transplants from wind damage and blowing sand and can help maintain higher bed temperatures by reducing heat losses from cold winds blowing over beds.

Most commonly rye is used because it is early and is tall compared to other small grains such as wheat or barley. There are several considerations when managing these rye windbreaks. In most cases the rye should be killed with a herbicide, most commonly paraquat, after it has reached full height. This is when the seed head has emerged. Consideration should be given to reduce the chance of seed formation which can become a weed issue in following crops (especially fall planted wheat or barley). When rye produces seed heads, and those seed heads begin to flower (pollen bearing anthers emerge from the seed head) and pollinate, there is about a 7-10 day period before viable seed is formed (seed is set). Burndown should occur before seed set.

If the field is to be followed with cover crop where there is no concern about the rye germinating in the field, then it can be allowed to go to maturity (normal between bed herbicide applications with shielded sprayers may still kill the rye before it reaches full maturity).

One issue with windbreaks is the movement of mites and insects out of the rye and onto the crop after it dies from burndown with a herbicide. Growers should be aware of this issue and plan for control measures during this burndown period if crops have already been planted. If windbreaks are allowed to mature naturally, this rapid outmovement of pests may be reduced initially but may be extended over a longer period.

For very early transplanted vegetables (April-early May) where rye windbreaks are between every 1-3 beds, the rye often is still elongating and may not have produce a seed head. In this situation, vegetables are transplanted before the rye is killed. The rye is managed with row middle herbicide treatments scheduled before vines start to run off of the plastic for vining crops such as watermelon or before staking for upright crops such as tomatoes. A shielded row middle sprayer is used and paraquat is added along with residual herbicide treatments.

For vegetables to be planted after rye has reached full height (May plantings), then a broadcast burndown with paraquat applied over plastic beds and windbreaks is often used. Transplating is delayed until a rain or irrigation has washed off the plastic. Do not use glyphosate for this type of burndown over plastic due the the potential for residuals washing into planting holes, affecting transplants

Where windbreaks are only in drive rows, then they should be killed before seed has set.

Vegetable Crop Insects – April 8, 2011

Friday, April 8th, 2011

Seed Corn Maggots (SCM) Control in Spring Planted Vegetables
We continue to observe flies actively laying eggs in a number of situations including recently plowed fields, especially when a cover crop is plowed under or when manure was applied to a field. Spring planted vegetables susceptible to maggot damage include cole crops, melons, peas, snap beans, spinach, and sweet corn. Control options can include commercial applied seed treatments, or soil insecticides; however, not all options are available for all crops. Please refer to the labels as well as the DE Commercial Vegetable Production Recommendations.

Cabbage
As soon as plants are set in the field, begin scouting fields for imported cabbage worm and diamondback larvae. As a general guideline, a treatment is recommended if you find 5% of the plants infested with larvae.

Peas
Be sure to sample for pea aphids as soon as small seedlings emerge. On small plants, you should sample for aphids by counting the number of aphids on 10 plants in 10 locations throughout a field. On larger plants, take 10 sweeps in 10 locations. As a general guideline, a treatment is recommended if you find 5-10 aphids per plant or 50 or more aphids per sweep. In general, aphid development is favored by cool, dry weather which slows beneficial activity but is favorable for the development of aphids.

2011 Wye Strawberry/High Tunnel Twilight Meeting

Friday, April 1st, 2011

Wednesday, April 13, 2011     6:00 – 8:00 pm
Wye Research & Education Center
211 Farm Lane, Queenstown, MD 21658
(meet at the Farm Operations Complex)

**Rain or Shine**

Hear: University of Maryland and USDA specialists discuss current research and other small fruit growing topics and “programmed production” of small fruit

See: Four small fruit high tunnel trials.

We’ll have refreshments and pre-registration is not necessary. If you need special assistance to attend this program, please call Debby Dant at (410) 827-8056 x115, no later than April 6, 2011.

For additional program information, contact Michael Newell, Horticulture Crops Program Manager, (410) 827-7388 or mnewell@umd.edu

University of Maryland programs are open to all citizens without regard to race, color, gender, disability, religion, age, sexual orientation, marital or parental status or national origin.