Christmas trees
Field crops
Fruit
Home and yard
Nursery and landscape
Turfgrass
Vegetable
Diagnostic Services
Soil/Plant Nutrient Lab
Enviro-weather
Regional IPM Center
Pesticide safety
Organic: New Ag Network
Invasive species
Sustainable ag & food systems
MSU ANR departments
MSU Extension
Site index
Contacts/permissions
| Vegetable Crop Advisory Team Alert newsletter | |||||||||||||||||||
|
|||||||||||||||||||
 |
|||||||||||||||||||
| Vol. 23, No. 3, May 7, 2008 | |||||||||||||||||||
| In this issue
Fusarium dry rot posing problems in potatoes Irrigation for frost protection Civil rights in employment decisions Michigan centennial farms certification Advice for morel hunters Regional reports Weather |
|
||||||||||||||||||
|
|||||||||||||||||||
| Fusarium dry rot posing problems in potatoes Fusarium dry rot is one of the most important diseases of potato, affecting tubers in storage and seed pieces after planting. Fusarium dry rot of seed tubers can reduce crop establishment by killing developing potato sprouts. There have been reports of Snowden seed lots affected in 2008 although other seed lots may also be affected. Growers should estimate the measure percentage of tubers affected by (see symptom section) and adjust planting rates as follows: (The extra percentage is to take in latent infection rates which for the sake of simplicity are doubled from the measured amount of infection.)
|
|||||||||||||||||||
| These recommendations are all based on estimations of what we have seen from experiments on Fusarium affected seed in the field for other (related) purposes. We have not modeled latent infection, but from observation we do often in our experiments weakened plants that are less productive than non-infected plants. The recommendation therefore for growers is based on our best guess of the real percentage of plants that may be infected. When infection rate is very high (less than 15 percent measured), growers should consider the option of not planting the seed lot as transmission may result in higher contamination rate and increase risk of severe reduction in plant stand and further contamination of the field. Symptoms The first symptoms of Fusarium dry rot are usually dark depressions on the surface of the tuber. In large lesions, the skin becomes wrinkled in concentric rings as the underlying dead tissue desiccates. Internal symptoms are characterized by necrotic areas shaded from light to dark chocolate brown or black. This necrotic tissue is usually dry (hence the name “dry rot”) and may develop at an injury such as a cut or bruise. The pathogen enters the tuber, often rotting out the center. Rotted cavities are often lined with mycelia and spores of various colors from yellow to white to pink (depending on the species of the pathogen several species of Fusarium cause dry rot). |
|
||
| Dry rot diagnosis may be complicated by the presence of other tuber pathogens. Soft rot bacteria (Pectobacterium spp.) often colonize dry rot lesions, especially when tubers have been stored under conditions of high relative humidity or tuber surfaces are wet. Soft rot bacteria cause a wet, slimy rot, which can rapidly engross the entire tuber and mask the initial dry rot symptoms. Dry rot also causes sprout death and when estimating the frequency of infected tubers growers should carefully examine the eyes (sprouts) to check if they are viable Cultural control Some level of Fusarium dry rot is almost always present in commercially available seed. Even though it is not possible at present to be 100 percent sure that a seed lot is completely free of dry rot, it is sensible to plant seed that meets established seed certification standards. Practicing the following procedures will help prevent dry rot:
Several products have been developed specifically for control of seed-borne potato diseases and offer broad-spectrum control for Fusarium dry rot, Rhizoctonia, silver scurf and to some extent black dot (Colletotrichum coccodes). These include Tops MZ, Maxim MZ (and other Maxim formulations + mancozeb) and Moncoat MZ. The general impact of these seed treatments is marked by improved plant stand and crop vigor, but occasionally, application of seed treatments in combination with cold and wet soils can result in delayed emergence. The delay is generally transient, and the crop normally compensates. The additional benefit of the inclusion of mancozeb is for prevention of seed-borne late blight. Studies at MSU have shown that the most effective control of Fusarium dry rot is achieved by the application of an effective fungicide, such as fludioxinil (Maxim-based products), prior to planting. Treatment of infected seed pieces with Maxim MZ (0.5 lb/cwt) at 10, 5 or 2 days before planting significantly reduced the percentage of diseased sprouts per tuber and significantly reduced seed piece decay in the varieties Pike and FL1879. Although it may not seem cost-effective to apply seed treatments to healthy seed, these results suggest that applying a seed treatment up to 10 days prior to planting can provide effective control of dry rot and increase rate of emergence, rate of canopy closure and final plant stand. Chemical control: Postharvest fungicides Mertect, thiabendazole remains registered for postharvest use on tubers. Few alternative compounds are available for potato tuber treatment in storage but include chlorine-based disinfectants such as sodium hypochlorite, calcium hypochlorite and chlorine dioxide. Limited information is available on the effectiveness of chlorine dioxide on potato storage pathogens, and results of some studies have suggested that chlorine dioxide does not provide effective tuber protection against Fusarium dry rot. Studies are under way at MSU to evaluate several of the new reduced-risk fungicides for use in postharvest applications. Some biological products have suppressed Fusarium dry rot in storage and include Serenade that is registered for foliar application to potatoes in the field. |
|||
| back to top |
|||
| Irrigation for frost protection
A farmer seeking to avoid crop loss from last week's freezing temperatures reported that in some fields, the irrigated areas received greater injury than plants along the borders where the sprinkler heads could not reach. This seems to contradict what we know about irrigation. Water from our wells is maintained at 50ºF to 55ºF, so any amount of water sprayed onto a field, it would seem, should help keep the air warmer than where no water was applied. In this case, our common sense fails us, because we are forgetting two very basic concepts from physics. What we forget is that: 1) when water freezes, it gives off heat to the surrounding environment, and 2) water that evaporates removes heat from its surrounds. If a farmer irrigates during freezing weather, but does not apply enough water to maintain continual ice formation, the water will not be giving up a great deal of heat to the air. Furthermore, if the soil's heat causes the water to evaporate, it will behave just like a refrigerator, removing the soils heat energy, resulting in colder air temperatures and more severe frost damage. If, on the other hand, enough water is supplied to keep ice forming, frost damage may be averted. Irrigation should begin as temperatures reach 33-34ºF and run until the ice melts. Nozzles that produce a mist are better at creating ice without applying as much water and soil saturation as with typical irrigation nozzles. Of course, there are limits to how much water should be used. Excessive ice accumulation can also injure plants. Those wanting a more thorough treatment of this subject can go to: http://www.ces.ncsu.edu/depts/hort/hil/hil-705.html http://ohioline.osu.edu/b672/pdf/Irrigation.pdf http://ohioline.osu.edu/aex-fact/0370.html http://tfpg.cas.psu.edu/40.htm |
|||
| back to top |
|||
| Civil rights in employment decisions While many federal laws protecting equal employment opportunity exempt small businesses, Michigan laws do not. Michigan laws protect religion, race, color, national origin, age, sex, height, weight, marital status and disability. As long as the specific disability is unrelated to the individual’s ability to perform the duties of a particular job or position with or without reasonable accommodation. Whether an applicant is a union member or an applicant’s veteran status also are questions that should have no place in employment decisions. Most laws apply to all employment decisions, including hiring, training, evaluation, promotion, compensation, discipline and termination. But questions on how to treat everybody fair and equally often come up during the selection process. As a general rule, all questions during the selection process should be relevant to the job to be filled. On an application form such questions may include name, address, phone number, the job the applicant is applying for and a summary of the applicant’s background (e.g., education and training, work history, special qualifications and skills). Citizenship and ethnicity are not typically relevant to agricultural jobs and therefore need to be avoided on application forms. An employer concerned about hiring applicants who will later fail to provide the required documentation for the I-9 form, may include a question in the application form such as “Are you legally eligible to work in the United States?” It is important to remember that many questions, which must be asked after a job candidate is hired, need to be avoided before the job has been offered. Everybody who participates in the hiring process must be familiar with the relevant qualifications, skills and experience of the job or jobs to be filled. Often times, small differences in how a question is asked differentiate a legitimate question from a discriminatory one. For example, “When did you attend college? When did you graduate?” could be construed as discriminatory on the basis of age; “How long did you attend college? Did you graduate?” are legitimate questions, if education is a relevant job qualification. By writing up questions before an interview, discriminatory practices can be avoided. In addition, interviewers should take notes during the interview in a neutral language. All interviewers must be trained how to ask legitimate questions and what topics to avoid with job applicants. If an applicant brings up any of these topics, such as family and children, disability or religion, it is best to not dwell on such information and to not ask any follow-up questions. The best practice is to follow the general rule to only ask job related questions and avoid all others, even if they legally can be asked in Michigan, such as sexual orientation. Also, interview questions should be similar for all job applicants. This information serves educational purposes only and does not constitute legal advice. For more information go to www.msu.edu/user/bitsch, under “News” click on “Civil Rights and the Hiring Process” or click on “Agricultural Labor Issues in Michigan” for a list of available newsletters. |
|||
| back to top |
|||
| Michigan centennial farms certification For those that have questions arise concerning centennial farms, there is an excellent website to highlight the heritage of Michigan farms. The website features how to certify a farm, what farms have been previously certified, what future events are upcoming, along with some supporting links and organizations. www.michigancentennialfarm.org |
|||
| back to top |
|||
| Advice for morel hunters Many people harvest morels who don’t hunt other mushrooms because morels are relatively easy to identify and there aren’t any other mushrooms that are easily confused with them. True morels have pitted caps rather than ridges or folds or wrinkles, and the morel cap is attached to the hollow stem at its base. The so-called false morels have caps attached only at the top end. Michigan State University (MSU) experts urge mushroom hunters to slice every mushroom lengthwise before cooking to verify your identification of it as a morel, and also to make sure there are no slugs or other invertebrates hidden inside the stem. Information on morels, morel hunting and proper identification of morels and other edible mushrooms found in Michigan is available in two Extension bulletins: “May is Morel Month in Michigan” (E-2755) and “Don’t Pick Poison!” (E-2777). Contact your local county MSU Extension office or order online at www.emdc.msue.msu.edu. |
|||
| back to top |
|||
| Regional reports 1 -- Southwest Ron Goldy Weather Temperatures for the period were generally above normal with lows from 26oF (April 30) to 58oF (May 2) and highs ranged from 58oF (April 30) to 80oF (May 6). Soil temperatures are averaging around 55oF. There was 0.75 inches of rain. Soil moisture is adequate for all field activities at this time. Crop report Asparagus harvest has recovered somewhat since the hard freeze on April 30 and a less damaging frost on May 4. Volumes are expected to be back to normal by the weekend. Damage on other crops, especially early planted cucumbers, was reported from the April 30 freeze. These crops have been replanted. Miscellaneous Field activity has increased as more sites are prepared. Fumigation and plastic laying continues. Planting of all crops has picked up now that the threat of severe cold weather appears to be over. |
|||
| back to top |
|||
| 2 -- Grand Rapids Area Weather Last week's frost damaged a number of transplants and emerging seedlings. Most will survive, but crops in some of these fields may mature less uniformly. Fortunately, the acreage with emerged plants was small. The first-picking asparagus crop in areas surrounding west-central Michigan was mature enough to be significantly damaged. A second, less severe frost event occurred on May 4, causing minor injury. It may also be worth a reminder to everyone that early-season cultivation can greatly increase the amount of injury during freezing weather. In non-cultivated fields, heat from the warm soil (relative to the air) is transmitted to the air at the soil surface, thereby protecting the seedlings. However, the porous, "fluffy", cultivated soil acts a bit like a sheet of fiberglass insulation, preventing the soil's heat energy from warming the air surrounding the threatened crop. Crop report Despite the chill, overall good weather has kept people and equipment in the fields. Most areas received enough rain to incorporate and activate herbicides, while preventing nitrogen fertilizers left at the surface from volatilizing off the fields as ammonia. Fields within 20-30 miles of Lake Michigan received more than three quarters of an inch, while areas farther inland had to settle for 0.3 to 0.5 inches. On muck soils, onion planting is mostly complete, with many fields showing emerged plants. Celery transplanting continues at a steady pace. Progress with leek, lettuce, beets and radish is good. Likewise, progress on upland fields is also good. Sweet corn is 20 to 30 percent planted. Cabbage transplanting continues, and warm-season vegetables are being placed in fields under plastic. Tillage and other field preparations continue. |
|||
| back to top |
|||
3 -- Oceana County Oceana County has had a relatively dry week with only about a quarter of an inch of rain last weekend. While temperatures have been above normal for most of the week, we did have patchy frost on May 4, but it did not appear to have caused any damage. Crop report The majority of the asparagus harvest will commence here tomorrow or Friday. The frost at the end of April really did not cost us any asparagus yield, particularly where rye cover crops held back emergence. We have had good rains since putting on our pre-emergent weed control, so weed control looks very good going in to harvest. I haven’t seen much white cutworm damage. Thanks to the economic down turn, our labor supply appears to be adequate so far. Growers are eager to begin harvest to take advantage of a hot fresh market. Early planted carrots are in the rabbit-ear stage and barley/oat cover crops are emerged and should provide good protection from wind damage. Planting continues, but is nearing completion. |
|||
| back to top |
|||
| 4 -- Mason-Newaygo counties Jim Breinling Weather Temperatures during the past week were more seasonal with precipitation occurring in the area mostly late in the day on Friday, May 2. Amounts recorded were 0.51 inch at Fremont and 0.37 inch at Ludington. Official low temperatures recorded the morning of April 30 were 22.4ºF at Fremont and 27.6ºF at Ludington. Unofficial low temperatures down to 18ºF were reported in some vegetable areas. Overall, damage to vegetable crops is reported to be minimal, but in some instances it is also too early to assess the extent of damage. Crop reports Significant spear growth was observed in asparagus fields yesterday in Mason County. Harvest should begin today or tomorrow. Carrot planting continues on schedule with favorable soil conditions. Here it is difficult to determine extent of damage, if any, due to the freezing temperatures. Planting of other crops such as potatoes, parsnips, and turnips continues. Planting of onions should be completed. An early planting of sweet corn under plastic was reported to show some leaf damage, but no plant loss. Summer squash planted under a high tunnel system also came through the freeze with some slight leaf damage, but no plant loss. |
|||
| back to top |
|||
| 5 -- Macomb, St. Clair and Lapeer counties Hannah Stevens Weather and crop conditions It has been a relatively cool and breezy week with maximum temperatures reaching the low 70’s and minimums in the low 30’s. The frost/freeze of one week ago did damage to a number of transplanted and seeded crops and another week will tell how well they will recover. Showers on Friday, Saturday and Sunday brought from 0.1 to 0.5 inches of rain to the growing regions, perhaps more to some; enough to disrupt the opening days of many farmers markets throughout the region. Plastic mulch is being laid on many vegetable fields. Seeding, transplanting and cultivation are underway. The earliest spring seeded barley on the organic soil was thinned a bit by the frost. At our current range of about 200 DD50, there are a number of vegetable pests making appearances. Crop reports Onions in seeded fields are in the loop stage. Early cabbage was set back by freezing temperatures. Unfortunately, imported cabbage worm adults (the white butterflies) are beginning flight and looking for places to lay eggs. Flea beetles are beginning to feed on foliage but in low numbers. I am working with a scout to monitor for cabbage maggot injury at one site and haven’t seen any eggs or maggot activity yet. Early carrots on the muck soils are in the rabbit ear stage. Barley cover crops are doing their jobs. Lettuce seems to have escaped the freeze for the most part and looks very good. Sweet corn emergence has been slow this week. Overnight temperatures have been in the 50ºF range. Corn, which had emerged, caught the freeze a week ago, but it seems it will recover as the growing point is still below the soil. |
|||
| back to top |
|||
| Weather news A relatively zonal, west to east jet stream pattern is expected across North America during the next one to two weeks, which should lead to an unsettled weather pattern across the Midwestern United States including Michigan. In the short term, the cool front that moved across the state Monday, May 5 is expected to stall near the southern border of the state, and serve as a focusing mechanism for showers and thunderstorms through the middle of the week. Best chances for rainfall have already happened in northern sections of the state late Tuesday, then towards central and southern sections Wednesday and Thursday. Precipitation totals and areal coverage are expected to be greatest across extreme southern sections of the state where precipitation totals through Friday morning may exceed 1-inch, but a larger section of the southern peninsula should get between 0.10 and 0.50 inches. Fair and drier weather is expected again by Friday continuing into the weekend. Temperatures will remain steady through much of the state from the low to mid-50's north to low 60's south. Low temperatures should fall from statewide levels in the 40's Wednesday morning to a range from the low 30's north to near 40ºF south by Friday morning. Some frost and freezing temperatures are possible in inland northern sections and some inner sections of the lower peninsula of the state later this week, especially Friday and Saturday mornings. Temperatures are expected to moderate (upward) a few degrees by Sunday, although means will likely still remain below normal. A weak low pressure system is expected to move over the state on Monday, temperatures will remain in the 50’s in the north to the low 60’s in the south, with morning lows in the upper 30’s to mid-40’s. Current medium‑range forecast guidance suggests more of the same recent pattern, with a series of upper air troughs moving eastward across the United States leading to an active storm track across the Great Lakes region. Both 6-10 day and 8-14 day outlooks covering May 12-16 and May 14-20 call for below normal temperatures and for above normal precipitation totals. Long lead outlooks New NOAA long lead outlooks for the upcoming few months reflect a significant weakening of the La Niña event that has been in place across the equatorial Pacific region since last fall. The outlook for the month of May calls for a continuation of an active storm track across the western and midwestern United States, leading to a forecast favoring cooler and wetter than normal conditions for Michigan and the Great Lakes region. However, given the recent weakening of La Niña conditions in the Pacific, there have been additional changes in the longer lead forecast periods (mainly moderations in precipitation forecast). For May through July, mean temperatures and precipitation totals in Michigan and much of the midwest are forecast to remain in the “climatology scenario” with near equal odds of below, near and above normal values. The outlook for the middle and latter parts of the upcoming summer is identical for Michigan, with more of the climatology scenario expected for both mean temperatures and precipitation. In a change from previous outlooks, only some western sections of the Midwest (e.g. sections of Nebraska and Kansas) are expected to remain drier than normal through the middle of the upcoming growing season. |
|||
|
|||
Email the web developer.