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The University of Maryland Extension Agriculture and Natural Resources Profitability Impact Team
proudly presents this bi-weekly publication for the commercial vegetable and fruit industry.
Volume 3 Issue 2 April 26, 2012
Spring Observations
from WyeREC
Strawberries:
 Field-grown plasticulture Chandler berries began
By Michael Newell
ripening this week. Continue fertility management as Horticultural Crop Program
indicated through leaf/petiole sampling and analysis. Manager, UME
Sampling should be done every two weeks during bloom and harvest. Peaches:
 Shuck fall is complete. Now and  Remember to consider resistant management when for the next several weeks, this choosing materials for disease and insect control. is an important period for peach Read and follow the label for all pesticides.
scab control. Sulfur can be used for brown rot control at this time, but materials that target scab (ie. Captan or others) should be used. Spring Vegetable Crop Update
 Fruit at this stage is also very susceptible to bacterial Vegetable Crop Insects –
spot. Favorable conditions for epidemics include Joanne Whalen, Extension IPM Specialist
persistent winds along with heavy rains or long periods of moisture or humidity. Coppers or Asparagus:
Terramycin should be applied any time wet and windy  Continue to check asparagus spears for eggs as weather is expected. Special Warning on
well as adult beetles feeding on spears. As a Phytotoxicity: Be very careful when tank mixing
general guideline, a treatment is recommended Captan and coppers. Captan/copper combinations if 2% of the spears are infested with eggs. Since should be avoided after long periods of overcast skies. adults will also feed on the spears, a treatment Also be careful with buffering solutions in tank mixes. is recommended if 5% of the plants are infested  Cat-facing insects, (tarnished plant bugs and native with adults. For a picture of asparagus beetle eggs, stink bugs) can be more prevalent in orchards that adults and larvae please refer to the following link: have weedy or clover ground covers. The first line of defense against these insects is a good ground cover management program. Although pyrethroids can provide good control of many insect pest at this time,  As soon as plants are set in the field, begin scouting for aphids, cucumber beetles and spider mites. When expect mite populations to increase if pyrethroids are sampling for aphids, be sure to watch for beneficial insects as well since they can help to crash aphid As a general guideline, a treatment should be applied Bloom is almost complete in apples. Recent rains for aphids when 20 percent of the plants are infested, induced the first scab infection period with a 2nd with at least 5 aphids per leaf but before populations infection period predicted for this weekend. Sprays for scab should also include materials for cedar-apple rust Potatoes:
As soon as plants emerge, be sure to sample fields for Later blooming varieties need to be protected for Colorado potato beetle adults, especially if an at planting FireBlight if weather conditions warrant anti-bacterial material was not used.  A treatment should not be needed for adults until you find 25 beetles per 50 plants and defoliation has reached Local Governments • U.S. Department of Agriculture It is the policy of the University of Maryland, College of Agriculture and Natural Resources, Maryland Agricultural Experiment Station, and University of Maryland Extension that all persons have equal opportunity and access to programs and facilities without regard to race, color, gender, religion, national origin, sexual orientation, age, marital or parental status, or disability.

together by a few strands of plant material. The use of Significant Seed Corn and Cabbage
treated seed or in-row banding of an insecticide gives Maggot Damage Possible in the
some control of SCM, however, replacing dead transplants is the only solution after SCMs kill a plant. Next Few Weeks
Once seed corn maggot damage is noticed, it is too late to apply control procedures. Thus, economic thresholds Jerry Brust, IPM Vegetable Specialist
are not useful and all management options are University of Maryland;
The unusually warm and dry spring we have had up to now has led many growers to transplant some of their melon and other vegetable crops early. The cool wet weather we have had in the last few days will make some of these fields vulnerable to seed corn maggots Delia platura (SCM) or less commonly found in cucurbit fields cabbage maggots, Delia radicum (CM). Both species overwinter in the soil as a maggot inside a brown case. In March and April small, grayish-brown Ric Bessin
flies emerge. Adult flies are most active from 10 a.m. – 2 p.m. and are inactive at night, in strong winds and when temperatures are below 50o F or above 80o F. Female cabbage maggot flies seek out and lay eggs on the lower portions of stems of young host seedlings or in nearby cracks in the soil. Within a few days the eggs hatch and the tiny maggots burrow down to the roots Ric Bessin
and begin feeding. SCM eggs are oviposited in soils with decaying plant material or manure. The adults are also attracted to the organic media around the roots of transplants and germinating seeds. That is why fields Figs 1, 2 and 3. Swollen stem of cucurbit plant with collapsed
that have been fumigated can still have problems with rotting roots. When stem is cut open the white maggots often
can be found.
SCM. Maggots will move into small stems and move up the plant causing a swelling of the stem just above ground level, while also causing root collapse and decay. If these stems are split you will usually find the white cylindrical larvae (figs. 1, 2 and 3). The adult flies are often found dead, stuck to vegetation during periods of warm wet weather (like we had in early April). These flies have been infected by a fungus, Entomophthora sp. These infected flies usually will be found at the top of a tall object in the field such as a grass seed head or a field-flag (fig. 4). Just before the fungus kills them they cement their body via their mouthparts to the tall object and die. If you look closely you'll see the body is filled with the white fungus that
Fig 4 Two SCM flies killed by a fungus
has ruptured between the segments (fig. 5). Being on a stuck to a field-flag via their mouthparts
tall object allows the spores of the fungus to move longer distances and infect more flies than if the fly had died on the ground. Even though we have had a dry spring, I still have seen many fungus infected dead flies this year. Unfortunately, the infection rate is not enough to reduce the SCM population and stop infestations. Soil temperatures two inches deep in the planting hole that are at or above 70o F reduce SCM egg laying and larval survival. If soil temperatures are above 70o F at planting but fall below this level for several days in a row (which they have just done), SCM adults will begin to oviposit eggs at the base of transplants. When wilted transplants are inspected in the field, maggots are often not found (they have already pupated), but their tell-tale Fig. 5 Adult SCM killed by a fungus - white strands coming out
damage can be seen as a hollowed out stem or root held for Pythium in tomatoes as well as Previcur Flex Scout Emerging Potato Fields for
(propamocarb HCL, 28) for the suppression of Pythium and Phytopthora in tomatoes and peppers. Phosphite Seed-Born Late Blight Infections
fungicides, such as ProPhyt and K-Phite (FRAC code 33) Bob Mulrooney,
can also be applied as a pre-transplant drench in the Extension Plant Pathologist; [email protected]
Additionally, there are a number of biologicals such as There have been several reports of late blight Trichoderma, Streptomyces, and Bacillus products which from Florida. The most recent was a report from can also be used in the greenhouse to help suppress north Florida in the Hastings area that was identified soil-borne pathogens. Remember, the biological need to early, fungicides were applied and the situation is under be applied without conventional fungicides. control. This is a reminder that there was late blight in At transplanting applications now include Ranman many of the seed producing areas last season. In spite (cyazofamid, 21) in the transplant water or through drip of all the precautions and seed testing that occurs to irrigation for Pythium control. There is a section 2ee for reduce the chance of seed tuber infections, infections the use of Previcur Flex (propamocarb HCL, 28) + can occur if the weather is right and the seed is Admire Pro (imidacloprid) in transplanting water for Pythium control. Presidio (fluopicolide, 43) now has a Be sure to be checking fields as they emerge for any label for drip application for Phytophthora control when seed born infections. Apply fungicide sprays of conditions are favorable for disease development. mancozeb or chlorothalonil once the plants begin to Additionally, phosphate fungicides, Pro-Phyt and K-Phite touch down the row. There is a late blight monitoring (FRAC code 33) can also be applied through drip website http://usablight.org/ that you can use to see irrigation at transplanting to help suppress Phytophthora what is happening around the country with late blight on blight. Unlike in the past, there are a number of good tomato and potato. options for early season control of these pathogens, it just takes a little bit more planning ahead of time. For further details on use and crop labeled please refer to Early Season
the specific fungicide label. Remember the label is
the law.
Pythium and Phytophthora
Control in Pepper and Tomato
Managing Forage Radish Cover
Andy Wyenandt, Specialist in Vegetable Pathology,
Crops that Fail to Winter-kill
Rutgers University;
Guihua Chen1, Ray Weil2 and Natalie Lounsbury2
University of Maryland, College Park
With the dry spring we've had thus far, it's easy to Departments of Entomology1 and Environmental
forget about Pythium and Phytophthora! The same Science and Technology2
question always comes up about this time of year when growers begin to start thinking about transplanting their Forage Radish and Winter-killing
tomato and pepper crops. "What should I do to help Forage radish, a winter cover crop now widely prevent Pythium and Phytophthora?". In years past, the adopted by growers in the mid-Atlantic region, provides answer was simple, apply mefenoxam (Ridomil Gold SL, multiple and unique benefits, compared to other cover Ultra Flourish, 4) or metalaxyl (MetaStar, 4). Problem crops. One of its most attractive features is that it solved, right? In the past, that answer was right, but achieves multiple benefits during its fall growth and then with resistance development in Phytophthora (P. capsici) is normally winter-killed. Its early winter-kill and rapid to both mefenoxam and metalaxyl, the correct answer decomposition also provides weed free, warmer and isn't so simple anymore. It's important to remember that drier soil conditions in early spring. This eliminates the both chemistries will work very well as long as resistance need for tillage/herbicide and allows earlier spring hasn't been detected on your farm. How do you know if you have resistance? The Generally, a cold period of several days with night easiest way is to follow efficacy. If the chemistries no time low temperatures below 20°F is required to longer provide the control they once did, then there is a completely kill forage radish. In Maryland, forage radish good chance you have mefenoxam-insensitive is usually frost-damaged in December and dies Phytophthora populations present on your farm. There completely during longer cold spells of January. The are also lab services which test for resistance. chances of achieving complete winter-kill can be Remember, once resistance develops it can linger increased by avoiding two conditions at cover crop around for a very long time. Therefore, proper crop planting that tend to make the plants less susceptible to rotation and resistance management is critical before frost. These are late planting and N deficiency. Younger, resistance has the chance to develop. Our options for later-planted and/or N-deficient forage radish plants will pre-transplant applications include a Ranman resist early frost damage. In addition, it seems to (cyazofamid, 21) drench one week before transplanting

require less severe temps to kill the plants early in fall additional assurance that the radish will not regrow. than later in winter as the plants seem to increase their Tillage is most effective in terminating the radish if it can cold resistance with repeated exposure to mild freezing be timed so that it is followed by a few dry sunny days. temps as the winter progresses. For non-organic systems, spraying a combination of During the 12 year period (2000-2011) during which 2,4-D (one pint) with glyphosate (one quart) should forage radish research was conducted in Maryland, good terminate the radish plants. An alternative is Gramoxone winter kill was observed in about 45 of 50 site-years of (at 2.5 pints/acre) combined with 2,4-D (at 1 pint/acre). research. Most of the instances in which forage radish When sprayed in 14 gallons of water per acre with re-grew in spring after partial frost damage in winter 7oz/acre of sticker, this combination gave complete kill were in the lower eastern shore or locations protected in less than a week (personal communication, Ron from cold winds. However, between Dec 2011-Mar 2012 Ritter). Another option is 8 oz of dicamba plus 1.5 qt of the eastern US experienced one of the warmest winters glyphosate. If radishes were planted in a small grain on record, with only four days (January 3, 4, 16, and 19) crop, they can be killed in spring using 0.5 ounce of
when the minimum temperature dropped below 20°F as Harmony Extra (old formulation) plus 0.5 pint of 2,4-D if
recorded at Beltsville, MD. (Figure 1). With this applied before small grain is in its jointing stage unusually warm winter, most of the forage radish in (personal communication, Steve Groff). Radishes are Maryland and other states in mid-Atlantic region was not also easily controlled by in-crop cultivation and by a completely winter- killed and grew back as temperatures wide array of herbicides available for post-planting rose in early March. Many farmers found they had green application in such crops as corn or soybean. cover crops where they were expecting only decaying In short, while the appearance of green re-growth in a residues. Some farmers had even interplanted forage field that was supposed to be winter-killed may look radish with their small grains. This situation created worrisome, any fall-planted radish that survives the much interest in how we can best terminate or manage winter will bolt very early in spring and should be quite forage radishes that failed to winter-kill. Methods and time to kill non-winter-killed forage
radish cover crop
Winter 2007-2011 Average
In most cases, leaves re-grew on intact or partially damaged roots or on the plants whose growing points were not damaged because of slow growth in the fall due to late planting and/or less available soil nitrogen. However, spring growth of forage radish, especially if tissues have been frost-damaged, is not nearly as aggressive as in the fall. Forage radish is not nearly as competitive in spring as other Brassicas, for example rapeseed (canola), can be. It is also much easier to terminate in spring than other Brassicas. Even though a lot of green regrowth in March may 1-Nov 16-Nov 1-Dec 16-Dec 31-Dec 15-Jan 30-Jan 14-Feb 29-Feb 15-Mar 30-Mar
look scary, the forage radish regrowth is easy to manage and should not pose any serious problems. Forage Figure 1. Variation of minimum temperature in the winters of
2007 -2011 and winter 2011-2012 at Beltsville Agricultural
radish regrowth in early spring can be killed Research Service, USDA, Maryland.
mechanically by mowing and/or tillage, or chemically by herbicides. With any of these methods, it will be best to wait for the radish to bolt – to send up a flower stalk. It is much easier to completely terminate the radish plants in the bolting or flowering stage as compared to the vegetative stage. New shoots may regrow from tubers left alive below ground if it is killed during the vegetative stage. Mowing is a practical method to terminate radishes in spring without disturbing the soil by tillage. If mowing for no-till radish regrowth control, the mower should be set as low as possible. One should avoid making tire tracks as far as possible - that is, it is best to mow when soil is firm and dry and the use of a side-mounted mower would be ideal. Otherwise, some radish tubers will just be bent over by the tractor tires and then missed by the mower blade. Mowing can completely control regrowth if applied at the right time and stage of Figure 2 Green regrowth from partially winter-killed radish
growth. Tillage after mowing can be used to provide

2012 Strawberry Twilight Meeting
Wednesday May 9th
6:00 – 8:00 PM
Wye Research and Education Center
211 Farm Lane
Queenstown MD
The 2012 Strawberry Twilight Meeting at the Wye Figure 3. Radish mixed in small grain in spring after radish
Research and Education Center will be held Wednesday, failed to winter-kill. This flowering stage is best time to
May 9, 2012 from 6:00-8:00 PM, rain or shine, at the terminate the radish.
Farm Operations Complex, 211 Farm Lane, Queenstown, MD. Directional signs will be posted. You'll hear University of Maryland and USDA small fruit experts discuss the current season's challenges and the impact that the new fruit pest may have on the industry. You'll see: USDA Moveable High Tunnel plots with plasticulture strawberry production; University of MD Strawberry High Tunnel plots with table top production demonstration and bio-fumigation trial; and Outdoor Plasticulture Fertility Trial plots with Chandler strawberries. We hope you can join us for an informative evening. Pre-registration is not necessary. Refreshments will be served. For additional program information, contact Mike Newell at 410-827-7388 or Figure 4 Regrowth from some radish tubers but not from
If you need special assistance to attend this program, others. Waiting until the radish bolts will make it much easier
to kill chemically or mechanically. These weak radish plants
please contact Debby Dant at 410-827-8056 or will offer little competition even if they are left alive.
University of Delaware
Small Fruit Twilight
Tuesday, May 22, 2012 6:00-8:00 p.m.
Carvel Research and Education Center
16483 County Seat Highway
Figure 5. These non-winter-killed radishes were successfully
Georgetown, DE 19947
terminated with a mixture of Gramoxone and 2,4-D after they
had reached the flowering stage.
Participants will have the opportunity to tour experimental plots and hear about current research on June-bearing and day-neutral strawberries, blueberries and blackberries. For additional program
information, contact Gordon Johnson at 302-856-
Commercial 2012
Vegetable & Fruit Headline News
Vegetable Productio
A bi-weekly publication for the commercial vegetable and fruit industry available electronically in 2012 from April through September on the following dates: April12 & 26; May 10 & 24; June 7 & 21; July 12 & 26; August 16; September 6 Maryland EB 236
On-Line at:
Published by the University of Maryland
Extension Agriculture and Natural Resources
Profitability Impact Team
Submit Articles to:
Also available in a new very interactive format at the Delaware Extension site at: R. David Myers, Extension Educator Agriculture and Natural Resources 7320 Ritchie Highway, Suite 210 Glen Burnie, MD 21061 Article submission deadlines for 2012: April 11 & 25;
May 9 & 23; June 6 & 20; July 11 & 25; August 15; September 5 Note: Registered Trade Mark® Products, Manufacturers, or Companies
mentioned within this newsletter are not to be considered as sole
endorsements. The information has been provided for educational
purposes only.

Source: http://notillveggies.org/VegetableFruitHeadlines3-2.pdf