Blog Description Copyright 2013 https://www.novavine.com/newsletter/rss Thu, 20 September 2018 10:36:00 Thu, 20 September 2018 10:36:00 https://www.novavine.com/newsletter/rss/newsletter/2018/september/20/resistant-vines-could-mean-less-vineyard-sprays/ Symposium focuses on breeding and developing natural resistance to vine disease By Linda Jones McKee This article originally appeared in Wines & Vines Suttons Bay, Mich. —Growing grapevines in the upper Midwest and New England is a challenging task in many ways. Winters can be long and quite cold; summers are often shorter than necessary to encourage full ripening of grapes; and too frequently there is an abundance of rain during some part of the growing season. One consequence of these conditions is the pressure from diseases such as downy mildew, powdery mildew, botrytis and bunch rot. It is not unusual for growers in a wet year to have to spray more than 15 times between bloom and harvest. Reducing the use of pesticides is a good idea from several standpoints: it’s cheaper, takes less labor in the vineyard, and makes the vineyard more sustainable. And now horticultural researchers are making serious progress in developing new varieties that are more disease resistant or locating those grapevines that are genetically more resistant. Paolo Sabbatini, an associate professor of horticulture at Michigan State University, received his doctorate from the University of Ancona in Italy and is well-connected with the viticultural research community in that country. He and Thomas Todaro, extension viticulture educator with Michigan State University, organized an international symposium on “New Cultivars for Disease Resistance and Increased Sustainability” on Aug. 29 that featured speakers from Michigan, California and Italy. One speaker, Clizia Villano, who is an assistant professor at the University of Naples, Italy, specializes in research at the molecular level. Villano’s research involves the interaction between powdery mildew and a grapevine’s genetic background, and she has found that some grapevines may have genes that help the vine resist powdery mildew. Her objective is to make the defense-oriented pathways more active after powdery mildew infection by crossing vinifera vines to be more resistant. The primary focus of the symposium, however, was on the work of the Vivai Cooperativi Rauscedo (VCR) breeding program and the resistant cultivars they have developed since Vivai Cooperativi was founded almost 100 years ago as a grapevine nursery. The goal of the VCR, which is located in the small village of Rauscedo just west of Udine in northeast Italy, is to provide vines for healthy, long-lasting and profitable vineyards, and over the years, they have provided grafted vinifera vines that meet those goals. Novavine, a nursery in Santa Rosa, Calif., has a license to propagate the new cultivars in North America.  The University of Udine began a breeding program in 1998 that focuses on disease resistance in grapevines so that the use of pesticides can be reduced, and vineyards can become more sustainable. The program has released 10 varieties which are now on sale from VCR. According to Enrico Peterlunger, professor of viticulture at the university, these vines have been planted in Eastern Europe, central and southern Russia, and China. When asked about the cold tolerance of those vines, Peterlunger replied that while they were bred to be disease resistant, the vines also appear to be more cold tolerant than expected. The symposium concluded with a tasting of wines made from the VCR grapes, including four white wines —Sauvignon Kretos, Sauvignon Rtyos, Fleurtai and Soreli — and a Cabernet Sauvignon and Merlot. Joe Juniper, owner of Vermilion Valley Vineyards in Wakeman, Ohio, commented on Facebook that “the wines I tasted were amazing. In a blind tasting even the most refined tasters would not be able to pick out these guys from their traditional parent counterpart.” Juniper noted that while the grapes are bred to be resistant to downy and powdery mildew, the fact that they have loose clusters may help to lower the amount of Botrytis and bunch rot that occurs as well. According to Sabbatini, the VCR selections have been through the cleaning process at the National Clean Plant Network and some vines should be available next spring. Larger numbers of vines will be ready for the 2020 growing season. Copyright © Wines & Vines Reprinted by permission https://www.novavine.com/newsletter/rss/newsletter/2018/september/20/resistant-vines-could-mean-less-vineyard-sprays/ https://www.novavine.com/newsletter/rss/newsletter/2018/september/20/resistant-vines-could-mean-less-vineyard-sprays/ Thu, 20 September 2018 10:36:00 https://www.novavine.com/newsletter/rss/newsletter/2017/october/20/what-to-do-in-the-vineyard-after-a-fire/ Recommendations from Jeff Wheeler for your vineyard after a wildfire #1 Burned areas should be reseeded before the heavy rains come, especially in areas with any slope.  I recommend an erosion control blend of seeds, which will generally include annual grasses.  Even on flat areas in vineyards it’s a good idea to re-seed as this will help tractor practices in spring.   #2 Determine if your vines are dead or alive.  After a fire, burned vines may still be alive depending on how hot they got. Fire can damage the vascular structure of a plant—in some cases the fluid that runs through the xylem and phloem will actually boil.  When this damage is widespread throughout the plant the vine will generally not survive.  A couple of weeks after a fire one can cut though the bark of the vine and observe the color of the vine interior to assess the condition. If the color is any shade of brown or black, this generally means the vine is dead. If the color is light yellow or green then the vine has survived the burn.  Many times the cordons or distill spurs will be killed while the thicker upper trunk sections will survive.  In these cases, cutting back the vines to the central trunk will be necessary.  #3 Ash in itself is not an issue for the soil or the vines but it can be so heavy as to coat leaves, which may cause reduced photosynthesis. The best way to remove ash from vines is to apply overhead water if possible. Wood ash will not be harmful to soil and can actually be a benefit as it contains potassium, magnesium, phosphorus and other minerals. https://www.novavine.com/newsletter/rss/newsletter/2017/october/20/what-to-do-in-the-vineyard-after-a-fire/ https://www.novavine.com/newsletter/rss/newsletter/2017/october/20/what-to-do-in-the-vineyard-after-a-fire/ Fri, 20 October 2017 13:23:00 https://www.novavine.com/newsletter/rss/newsletter/2017/january/20/salt-damage-in-the-vineyard/ Insights on mitigating sodium chloride issues from Dr. Andy Walker of the Department of Viticulture and Enology, University of California Davis and Novavine viticulturist Jeff Wheeler Saline conditions in both soil and irrigation water have always been an issue in agriculture. This is even more the case in semi-arid, drought-prone areas like California. Whether it’s sea water intrusion into existing wells, the higher concentrations of sodium and chloride in ground water as it recedes further downward, or the fact that new wells have to be drilled into less desirable aquifers, irrigation water is becoming more saline in many areas.  Minor sodium chloride toxicity can express itself in grapevines as suppressed growth, generally due to lower photosynthesis and compromised mineral nutrient uptake. It can also be expressed by lower fruitfulness, smaller cluster size, reduced brix, and delayed ripening—among other maladies. Higher concentrations of sodium chloride are expressed as even more extreme symptoms that can eventually lead to vine death.  Leaching and soil amendment Mitigating salinity issues is possible, but can be complex.  Chloride can easily be leached from the soil profile. With ample amounts of non-saline water, chlorides will move through and out of the root zone. Soils that are sandy in texture need less clean leachable water than those soils that contain more clay. Due to its positive charge, sodium does not leach as easily through the soil matrix.  Sodium’s relatively small size and positive charge causes soil particles to be tighter and less porous. This along with its tendency to bind to negatively charged soil particles makes it difficult to leach.  Additions of gypsum (calcium sulfate) late in the season—so as to allow winter rains to move it into the soil profile—are important.  This process causes the sodium to be bound to the sulfate in gypsum as sodium sulfate.  This sodium sulfate moves out of the soil profile much easier than sodium itself.  This sodium sulfate molecule frees up more calcium that will help with soil porosity, allowing greater water infiltration and leaching.  Rootstocks Rootstock choice is a great strategy to mitigating saline conditions.  According to Dr. Andy Walker, Department of Viticulture and Enology University of California Davis, chloride exclusion is the most important aspect for saline tolerance in grapevine rootstocks.  Of the current rootstock choices, 140 Ruggeri and Schwarzmann are the two best choices for chloride exclusion and thus salt tolerance.  The graph below depicts different rootstocks and their relative chloride exclusion.  Those with lower chloride percentages represent better salt tolerance.  One will notice names or numbers that do not correspond with current available rootstocks, such as OKC.  These represent potential future rootstocks and salt-resistant selections that Dr. Walker and his team are currently researching.  Many have great promise when it comes to saline tolerance and future commercial availability is on the horizon.  Shadehouse screen, 75 mM NaCl Saline conditions are an ever-present issue when it comes to farming.  While this condition has the potential to make farming more difficult it is now possible to mitigate many of these issues.  A complex solution involving all management practice, amendments, rootstocks etc. is recommended. https://www.novavine.com/newsletter/rss/newsletter/2017/january/20/salt-damage-in-the-vineyard/ https://www.novavine.com/newsletter/rss/newsletter/2017/january/20/salt-damage-in-the-vineyard/ Fri, 20 January 2017 10:50:00 https://www.novavine.com/newsletter/rss/newsletter/2016/november/17/red-blotch-update/ We know the alfalfa hopper was positively confirmed as a vector for GRBaV.  What is your opinion as to the possibility of other vectors?  Mysore: There are other members of family Membracidae in the vineyards.  It is possible that there might be more than one vector species that can transmit GRBaV.  We need research data to confirm this point.  Even if two or more tree hopper species turn up as vectors under laboratory/greenhouse conditions, their significance in terms of virus epidemiology in vineyards also needs to be determined. For many years there has been speculation of vine to vine transmission of viruses, such as LR3, mainly through root grafting in grapevines.  What is your opinion on this form of vectoring of viruses, GRBaV in particular? Mysore: You have already indicated that LR3 transmission by root grafting was a speculation.  I failed to see any scientific evidence to support this theory in case of LR3.  Root grafting has been shown to be a way of virus transmission in case of several perennial crops.  This is certainly a route in orchards planted with stone fruits.  My search using Google scholar indicated that the viruses suspected to be transmitted this way were invariably capable of mechanical transmission.  One grapevine virus in California that may fall into this category would be Grapevine fanleaf virus.  Even for this virus, there is no documented evidence of transmission by root grafting between grapevines.  GRBaV is not known to be transmissible by mechanical inoculation and thus may not get transmitted by root grafting. We know there are two distinct clades of the GRBaV virus.  Do you have any further updates on these clades, or strains?  Do you see one being vectored easier or quicker than the other. Mysore: We are working on this at this stage and experiments are in progress.  The field study we have planned may take several years to provide the data.  Based on available data, it appears that Clade 2 isolates are most widely distributed.  Based on this one can assume that Clade I is less efficiently transmitted.  Again, there is no data documented that can distinguish from infection due to contaminated planting stock from those due to transmission by a vector.  I need to emphasize that we still need to document data for transmission by vectors under vineyard conditions.  We have noticed in some areas of the state that the virus seems to move faster than others.  Do you see this as well and what do you feel are some of the reasons behind this? Mysore: The only thing that seem to correlate well with the virus spread is the presence of riparian areas and irrigation reservoirs in or close to vineyards. It is tough to separate the grapevines that came to the vineyard as grafted versus those that got infected at the site.  All the blocks where we had a base line for the diseased grapevines were removed.  We started monitoring again since last year.  At this stage, we do not have sites where we have clear documentation of spread rates.  Also, we need to be aware vineyard practices that can influence the spread in a given location.  Prevalence of vector species and their off season hosts, pest management practices, location of riparian areas, irrigation reservoir, cover crops, use of machinery and sprays that can potentially influence probing behavior of the vectors.    I know that certain viruses will express more or less, depending on temperature, GFLV and Fleck, to be exact.  We are seeing that certain areas have no issues with ripening GRBaV positive fruit.  Do you feel that GRBaV might have a temperature dependency? Mysore:It is very likely that GRBaV might have a temperature dependency.  However, we need to separate the effects of virus on vine performance into different categories and consider each one from the point of vineyard productivity.  These are (1) symptoms, (2) yield parameters, (3) TSS content, and (4) wine quality indices (I am not an expert on this to list them individually).  We have noticed that the RB symptoms can vary with temperature, but during these years we also had a drought.  The unpublished data that we collected in a winery in 2012 and 2013 indicated year to year difference in TSS content in the same vines.  This was also noticed at Oakville station also.  We have also noticed that RB symptoms are pretty similar on a given cultivar whether it was in North Coast, Foot Hills or Central Coast.  We all know that these regions do not have the same weather conditions.  On some cultivars we have noticed effect on fruit yield in some locations, but this may not be factor in the North Coast where the crop is thinned to produce quality wine.  TSS is one parameter that generally dictates the harvest time. It is possible that some areas where RB was noticed, the fruit had no issues with maturity.  Were those with RB and without RB had the same TSS even though both were over 24 °Brix (required for wine making)?  What about other wine quality parameters?  I was told by a winery that even though they did not see much of a problem with the TSS, there were differences in anthocyanin and other volatiles.  What is the life cycle of the alfalfa hopper, and where and what stage do they overwinter?  Frank: There is little data on 3CAH on grapes and very little from alfalfa California, so what we know comes primarily from crops in the southern US. From those studies, it would seem that there might be 3 generations a year, and in those studies some say that they overwinter as eggs or as eggs and adults. We have been intensively sampling a vineyard in Oakville weekly since March to determine more about the life cycle and will also be sampling a couple of sites with different weather patterns over this winter to try to determine how they overwinter. What is the cover crop impact on hopper populations in the vineyard?   Legumes vs grasses?  Frank: We are initiating a study of different cover crops for this winter that will allow us to begin to answer this question – especially legumes vs grasses vs others. We assume that cover crops will influence 3CAH populations in vineyards, but the impact may be positive or negative depending on how they are managed. There are no data at all on specific impacts or management. What would you recommend as far as chemical control of the pest, material and timing?  Organic controls?   Frank: What chemicals that are effective are known from studies on alfalfa, soybeans and peanuts in the south. Many of these chemical are either not registered on grapes or are not things that we would want to use because of their toxicity profile to beneficial organisms. We are doing a small study at this time to determine if there are chemicals that might be a good fit to the grape system, and hope to do more next year. In terms of optimal timing, that is not known since we are only now learning about biology of the hoppers in grapes. How efficient do you feel the hopper is as a GRBaV vector? Frank: We have only begun to determine parameters for acquisition, persistence and success of transmission as related to time of year. It will take some time be able to answer this with any precision.  Is the alfalfa hopper a phloem feeder, or xylem, mesophyll etc.? Frank: It is primarily a phloem feeder. Many growers have noted the absence of alfalfa hoppers in vineyards where GRBaV seems to be spreading at high rates, do you suspect another vector of the GRBaV? Frank: 3CAH occurs at quite low densities in vineyards, even those that we have sampled where there is documented spread, so it is very easy to overlook them. It is easier to find the girdles that they make when feeding on the vines, so that is a better indication that they are there. However that is a less than optimum way to sample for management purposes since they have already been feeding. They are not very attracted to yellow sticky cards either – we have been running them all this season and the cards do not reflect the population that is present. We do not know of another vector, but are currently conducting transmission studies of other treehopper species that we have seen in vineyards. https://www.novavine.com/newsletter/rss/newsletter/2016/november/17/red-blotch-update/ https://www.novavine.com/newsletter/rss/newsletter/2016/november/17/red-blotch-update/ Thu, 17 November 2016 14:45:00 https://www.novavine.com/newsletter/rss/newsletter/2016/04/04/cation-exchange-ph-and-base-saturation/ Soil sampling is a critical tool for any farming operation.  It not only helps determine your fertilization plans for the following growing season, but it will also aid in determining the long term strategy for building sustained soil health.  This article will address three key parameters available in a soil test that best aid in improving agricultural soils over the long term, and also have relevance in the short term.  These parameters are pH, cation exchange capacity and base saturation.  It is important to ensure that your soil report includes all three of these categories. Taking and deciphering a soil report is a relatively quick and easy task.  Post-harvest fall sampling is the best time to capture the information in a soil report, but any time of year is acceptable.  There are two distinct ways to sample by spatial means: grid and zone.  In basic terms, grid sampling is best conducted on properties that are relatively uniform (homogenous) when it comes to soil texture and type.  Zone sampling should be conducted when soils are varied (heterogeneous) in texture and type.  Grid sampling is done in equally spaced samples throughout the field where the field has consistent growing potential.  Zone sampling takes into account soils that will have drastically different growing potential in specific areas within a field and should be sampled as such.  Once the sample has been taken and sent off to the lab, it makes sense to not only test for the three key factors we are discussing, but to also test for macro nutrients, including nitrogen, phosphorous and potassium,  and secondary micro nutrients.   The first item to evaluate should be pH.  The effects of pH are far-reaching; most nutrients will become either more or less available according to the pH level.  Phosphorous is a good example.  At a pH of 6 to 6.5, phosphorous is easily available to plants when there is a sufficient level of it in the soil.  However, as pH moves higher—becoming more basic—phosphorous becomes less available.  At a pH near 8.0, phosphorus becomes almost completely unavailable to plants.  The good news is that pH can be adjusted in both directions with little work.  In acidic soils with low pH, adding lime is a quick and easy way to adjust pH upward. Basic, or high pH, soils are a little more difficult to adjust.  It’s common in soils with pH near 8 for growers to add acids, such as sulfuric, or phosphoric acid, to irrigation water.  Adding elemental sulfur is another means of lowering pH in soils. The next soil component to evaluate is cation exchange capacity, or CEC.  CEC is a relative measure of the soil’s negative charge and thus its ability to hold certain nutrients that are cations (positively charged in nature). There are only a few components that give soil a negative charge; the two most common are clay and organic matter.  Elements such as calcium, potassium, magnesium, and others are cations and have positive charge.  CEC levels will give a grower a good idea of the overall nutrient capacity as well as soil texture.  High CEC, in the range of 25 and above, represent clay dominated or fine soils.  Soils with a CEC of 10 or less are sandy or course in nature.  This can have great ramifications on farming practices such as fertilization and irrigation.  Fine, or clay soils retain nutrients better than sandy soils.  Course, or sandy soils have little charge and are worse at holding large quantities of nutrients.  Fine soils can be fertilized less often, where course soils should be fertilized in small, but frequent doses.  Fine soils hold a great deal more water than course soils.  Therefore fine soils can be irrigated less frequently than course soil and are more prone to becoming waterlogged.  CEC is very difficult to alter, but by utilizing certain tools one can work around most of the problems encountered.  As an example, an effective tool for high CEC is to add gypsum to create better porosity, thereby creating better drainage.  Another mitigating technique can be to add drain tile to alleviate water logged soils.  In sandy, low CEC soils, the annual addition of organic matter in the form of manures, composts and compost teas helps build better charge, better water retention and increases microbial numbers in the soil.   Base saturation is the final item to focus on as it also has ties to CEC.  The importance of base saturations cannot be overstated.  In general, the term refers to the level of permeation of soil surfaces by five cations, calcium(Ca), magnesium (Mg), potassium (K), hydrogen (H) and sodium (Na). Each of the cations will be represented as a percentage on the soil test.  What is important is how these percentages relate to one another.  Ca should be 60 to 65%, K 4-6%, Mg 12-25%, H 10% or less, and Na less than 1%.  If any of these cations are out of range than the grower should work to alter the percentages.  For example many soils in California are high in Mg and lower in Ca.  An easy way to alter this is the application of gypsum, calcium sulfate or lime (calcium carbonate).  The addition of these materials will not only aid in the addition of elemental Ca, but facilitate the removal of excess Mg from the soil profile.  Excessive H on the base saturation generally points to acidic soils which can be altered by liming the soil.  The addition of a host of mineral nutrients to the soil to aid in plant nutrition is of little use if your base saturation percentages have not been addressed before hand. https://www.novavine.com/newsletter/rss/newsletter/2016/04/04/cation-exchange-ph-and-base-saturation/ https://www.novavine.com/newsletter/rss/newsletter/2016/04/04/cation-exchange-ph-and-base-saturation/ Mon, 04 April 2016 15:36:00