| Potato Crop Update - #1, May 28, 2003 |
|
Update on potato crop growth and development in the Central Sands. A.J. Bussan, Vegetable Specialist, UW-Madison, Horticulture Potato Disease Update. W. R. Stevenson, Department of Plant Pathology, UW-Madison Note on Healthy Grown Program – Deana Sexson, NPM Program, UW-Madison |
| Update on potato crop growth and development in
the Central Sands.
May 27, 2002. A.J. Bussan, Vegetable Specialist, UW-Madison, Horticulture Telephone 608-262-3519, cell 608-225-6842, e-mail ajbussan@facstaff.wisc.edu |
|
Potato production season for 2003 has started with good planting and early growing conditions. Much of the crop was planted in a timely manner in the Central Sands as weather conditions did not interfere with field work through much of April. Soil conditions may have been too dry over the last 1 to 2 weeks of April so some growers irrigated fields prior to planting. The irrigation ensured moist soil conditions to allow for rapid crop development, but more importantly minimize the potential for seed piece decay.
Early planted potatoes began to crack and emerge on approximately May 15 in plots at the Hancock Agriculture Research Station. This corresponds to 7 to 14 days earlier than in 2002. Total P-day accumulation from May 1 until May 27 was 130 to 160 units during 2003. In contrast, only 80 P-days had accumulated by the end of May at the Hancock Agricultural Research Station, during 2002.
Walt Stevenson and several growers expressed concerns about dry soil conditions followed by heavy rains leading to development of seed piece decay. I have not seen stand reductions due to seed piece decay in plots at Hancock, but we will not count emerged plants until the first week of June. Seed piece decay can also lead to reduced vigor of early growing plants. I am optimistic that warm soils and rapid emergence reduced the potential for seed piece decay.
McCain foods surveyed a number of contracted grower fields this spring and quantified the severity of the plow pan across the Central Sands region. A number of growers have used deep rippers, para-tillers, or other deep tillage equipment to break up the plow pan with some success. There is concern that the plow pan may limit root development and water movement through the soil. The underdeveloped root system and wetter soils are hypothesized to increase the incidence of potato diseases such black dot, pink eye, and others. Previous research by Tanner and Curwen documented little benefit in terms of potato growth and rooting when utilizing deep tillage equipment. However, they did not monitor potato diseases and soil conditions may have changed based on changes in production practices since that research was completed. We will monitor the influence of deep tillage on potato growth and development and disease development in several field scale experiments this summer, as well as in a small plot trial at the Hancock Ag Research Station.
With crop emergence occurring a couple of weeks ago, many growers have already finished hilling. The optimal timing for potato hilling has been moved ahead in recent years to minimize root pruning and prevent root/soil borne diseases. Obviously, hilling potatoes earlier in the season will minimize potential root pruning. However, hilling after the second fertilizer application (3 wk after emergence) allows for optimal fertilizer placement over the potato rows. Secondary or repeat hilling is not recommended unless heavy winds or rains deform potato hills.
Some growers are experimenting with different hilling equipment this summer. The design of the new potato hiller is intended to run a deep shank through the furrow followed by paddles intended to create divots and ridges. The goal of the alternative hiller is to help break the plow pan and create a better hill for root and tuber development. The new hill creates more space for tuber development and also reduces the surface area of the hill. Thus, the hill temperature may be cooler as more of the hill may be insulated from high air temperatures and protected from direct sunlight. In addition, the uneven furrow is intended to allow for improved water infiltration and reduced runoff from hill slopes and prevent excess water or pooling in low areas within the field.
Growers will need to monitor potential ET as rapid canopy development will begin to increase the demand for tight irrigation management. As always, estimated ET and P-day accumulation is available from the climatology group in soils. Please contact me if you have difficulty receiving this information.
ON WISCONSIN |
| Potato Disease Update - W. R. Stevenson, Department of Plant Pathology, UW-Madison, Tel. No. 608-262-6291, Email: wrs@plantpath.wisc.edu |
|
Another season is now underway and off to a good start. As I am taking a windshield tour of Central Wisconsin, I note that most early planted fields are now emerging and some of the earliest planted fields are now approaching 10” tall. Emergence for the most part looks good. In spite of exceptionally dry conditions at planting, many growers took steps to minimize seedpiece decay by irrigating their fields before planting. Planting suberized seed into moist soil is a good recipe to avoid seedpiece decay. Many growers have treated their seedpieces with fungicides such as Maxim MZ, Tops MZ or Moncoat MZ to aid control of Rhizoctonia stem canker. Still other growers have used in-furrow treatments such as Moncut, Blocker or Quadris to help control this fungus-incited disease that can lead to delayed emergence, brick-red lesions on below-ground stems and weak plants. Some growers are also interested in reducing infection of black dot disease by using seedpiece or in-furrow treatments with fungicide. As we go through the growing season, keep an eye on the health and vigor of your plantings, especially in fields where side-by-side comparisons of fungicide treatments are possible. In cases where you are seeing observable differences in stand, Rhizoctonia stem canker, plant vigor or sign and symptoms of black dot, I would be interested in taking a look and visiting with you.
It won’t be too many weeks before we begin to turn our attention to treatment for early and late blight control. Our weather network with stations in the potato canopy at Grand Marsh, Hancock, Plover and Antigo is up and running. Our website at http://www.plantpath.wisc.edu/wivegdis/index.htm is updated every 2-3 days with the most recent weather data and current summation of Severity Values and P-Days. At the moment, for fields emerging in the Hancock area on May 13, we’ve accumulated 76 P-Days and 2 Severity Values. Hopefully the accumulation of Severity Values will remain very low for the next few weeks. The outlook for continued dry weather along with timely rains will help. As I look at the late blight risk this year, my sense is that the risk is as low as it’s been for a few years. No late blight was reported in the primary areas where Wisconsin growers purchase their seed. Thus the risk of bringing in seed with “just a little late blight at a bargain price” is low. Last year’s weather conditions in Wisconsin were not highly favorable for late blight development for much of the growing season. While we observed some late blight in early July and then some additional spread during late August, much of the state was free of late blight. Very little late blight was observed or reported in storages this winter. Cullage of infected tubers during shipping was spread this past winter and had ample opportunity to freeze and melt away. Thus there should be no cull piles lurking in the back forty that could be sources of the late blight pathogen. If anyone knows of possible cull piles, they need to be destroyed immediately so that they are not potential inoculum sources. By state administrative rule, all cull piles must be destroyed by May 20.
Resistance management should be on everyone’s mind this year, especially when using strobilurin fungicides such as Quadris, Headline and Gem. There will be a Common Tater article in June that focuses on this issue. For the moment, however, here are a few suggestions. For those growers who will be applying Quadris as a banded application to recently emerged plants for management of black dot, your first early/late blight spray should NOT be a strobilurin fungicide. You should not be treating with strobilurin sprays in back-to-back applications, even if you are mixing a strobilurin material with mancozeb, chlorothalonil or metiram. Data from our research program suggests that three treatments with a strobilurin material alone or mixed with another fungicide chemistry (mancozeb, chlorothalonil or metiram) and then treating with any of these materials alone for the remainder of the growing season will provide good control of the primary foliar diseases. In periods with a high risk of late blight, we have many options including Curzate, Acrobat, Previcur Flex or Omega, all mixed with mancozeb, chlorothalonil or metiram. We also have Gavel (contains mancozeb) available for use. All of these products are effective in managing late blight. We will continue to monitor isolates of the early blight pathogen for the response to specific fungicides. Data from our surveys help to keep our disease management recommendations current and help to insure that our recommendations are effective in grower fields.
We have multiple trials out in the state focusing on multiple aspects of disease control. Trials are located at the following locations:
We also have multiple trials involving carrots, snap beans and pumpkin that make this summer both interesting and challenging. As always, our trials are open for your inspection. Plot plans are available at the specific sites. If you would like a personal tour, let me know.
|
|
Note on Healthy Grown Program – Deana Sexson, NPM Program, UW-Madison. Tel. No. 608-265-9798 – office and 715-340-3347 – cell, Email - dlsexson@wisc.edu |
| There is still time to sign up potatoes for the Healthy Grown program to be certified under the Protected Harvest eco-label for the 2003 growing season. Healthy Grown sales have greatly improved between 2002 and 2003, and we are looking forward to another good year. Certification involves field records and documentation as well as an on farm audit. If you are interested in working with the program, call Deana Sexson at 608-265-9798 or e-mal at dlsexson@wisc.edu or contact Mike Carter. Certification documentation can be received by Rochelle Kelvin at (410) 757-4234 or Rochelle@protectedharvest.org. |