THC GROWERS' NEWSLETTER June 2000 Rick Hamman, Office: 786-4557, Cell: 781-1401, Fax: 786-4580, E-mail: rickh@hoguethc.com SEASON UPDATE: Hail in Walla Walla, tornados in Zillah, and a non-damaging May 6th record low (33oF at Hanford) makes this an unusual start to the season in Eastern Washington. Other than these peculiarities, the climate for May has been very close to normal. According to Pacific Northwest National Laboratory at Hanford, May's average daily temperature was only 0.1 degree below the normal (61.3oF) for this time of the year. Shoot development for most varieties appears to be running about a week ahead of last year. Total precipitation for March through May (2.28 inches) was ahead of the normal (1.40 inches). Last weeks rain in most sites has slightly delayed soil moisture depletion. A week or so of warm weather could easily turn that around and growers should be keeping a close eye on shoot growth activity. IRRIGATION: Wine grape yield and quality are affected by climate, soil, genotype and cultural management practices including irrigation. Poor irrigation management can result in water stressed or overly vigorous vines resulting in unbalanced growth, reduced yields and inferior fruit quality. Eastern Washington during most years has a dry climate that lends itself to superb vineyard irrigation strategies. In recent years, most growers have moved from the age of gravity flow furrow systems to sophisticated drip, micro-jet and solid set irrigation systems allowing for more precise applications. These modern irrigation systems are suppose to be easy, but? Even with high tech irrigation systems, soil moisture probes and regulated deficit strategies; vineyard block uniformity can be a problem. Fine-tuning the entire irrigation management system to your particular site is extremely important and more involved than simply turning a switch on. Most growers have made great advances with regulated deficit irrigation strategies and continue to improve on this technique. However, it is an error to assume that one irrigation strategy fits all grapes (reserve, red or white) in all blocks. Over watering one block to prevent stress in another is sometimes unavoidable but may require different planning and scheduling of water application. Additional zones, individual valves or alternate trellising may need to be installed. For example, this year I know of a CH block on a poor dry site (shallow, sandy soils etc.) that has been irrigated (1- set/week) for 5 weeks to develop an adequate canopy, while adjacent is a Syrah block in a lower area with heavier loamy soil and a vigorous 40 inch canopy that has needed virtually no irrigation. These two blocks were on the same zone but have since been valved separately for more control. Differences in each block such as soil depth, soil texture, slope, drainage, variety vigor, trellis system, training system (S-D vs. VSP etc.), cover crops, weed control and the weather all exist and play important roles in fine tuning your system. Simple procedures to help customize your system like installing in-line valves; plugging emitters or installing extra emitter/vine can help enhance vineyard uniformity in existing systems. Another method is to measure shoot growth each week. This is an inexpensive but very reliable procedure to determine when growth has slowed and irrigations should begin or shut down. Making big differences in canopy development, berry size and fruit quality by irrigation is great if carefully managed but can be costly if not. Vines with full canopies can quickly develop water stress during late season and cause berry shriveling, yield and quality loss that a simple procedure like explained above could have prevented. If you have questions regarding irrigation of your vineyard, please contact me. INSECTS: Mealy bug incidence has been low - moderate, again leading to only a few recommendations for control. Thrips and cutworms also have only been observed in low levels resulting in very few blocks being sprayed. First brood Leafhoppers should be fully emerged by mid June. We are seeing very few of them to date. Consider treating if nymphs exceed five on basal leaves of random samples. Provado is the material of choice for hopper control. Once again, several blocks that were treating for MB with Lorsban early have exhibited some minor leaf burn. MILDEW: Weather conditions have been very favorable for mildew potential during most of the month of May. At Hanford, a total of 0.77 inches of rain fell compared to a normal level of 0.51inch. Preventative control spray programs as noted in the April newsletter should be well under way. Several growers have questions regarding fungicide efficacy and whether or not to reapply after a rainfall. Generally speaking, nearly all systemics will retain their fungicidal activity if allowed to completely dry before rainfall occurs. Contacts on the other hand will need to be reapplied if a good soaking rain occurs soon after applying. PETIOLE SAMPLES: We will be pulling tissue samples for nutrient status at full bloom. As of Friday June 2, flower development for Chardonnay grown at warmer sites (Whaluke slope, Tri-Cities) is between 50 – 80% full bloom. We plan to begin in the warmer sites the end of next week (June 8th). We will be sampling most but not all blocks. If you have concerns about specific blocks, contact us to see if we can coordinate efforts. We will again be using US Ag in Pasco for the analyses. CROP ESTIMATION: We will begin our crop estimation program the week of July 5th. We will be counting clusters, harvesting and weighing immature fruit in every block to determine cluster numbers and to estimate harvest cluster weights. In representative blocks, we are also taking berry weights to help determine relative cluster size. Once this process is complete, we will use this information to convey thinning suggestions to growers. Hogue strongly encourages growers to collect their own data for comparison to our results. If there are significant differences, they will be reconciled through a meeting between the winery and grower representatives at the vineyard. It is our intent to have this information to growers by 7/24 and expect thinning to be completed by 8/15 at the latest. Remember that any delay in thinning past veraison reduces the benefit for ripening, especially in cool years. We will resample blocks after thinning to fine tune our crop estimation assessment. THINNING: Always consider variation in a given block and a range in clusters per vine. Our sampling primarily addresses the average cluster number of "typical" vines. When a recommendation is made to drop a given number of clusters per vine, this too is an average amount. Therefore, vines at the high end of the range should have more clusters removed than specified, while vines at the low end should have fewer clusters removed. Second, the distribution of fruit on the vine needs consideration. Fruit should be uniformly distributed along the cordon, with few clusters touching each other. Areas of cluster bunching should be thinned out preferentially. This is especially true for Merlot and rot-prone varieties, such as Riesling, Chenin blanc, Chardonnay and Sauvignon blanc. If thinning from the east side of the vine, fruit in the canopy interior (i.e. shaded) should be preferentially removed. Conversely, if thinning from the west side, fruit on the exterior (i.e. sun-exposed) should be removed. Third, if red varieties are being color thinned during veraison, the least colored (i.e. greenest) fruit should be removed. CANOPY MANAGEMENT UPDATE: The following are our recommendations for cordon suckering, movable catch wires and leaf removal for the season: CORDON SUCKERING: Cordon suckering should be finished by bloom. If you are uncertain about this procedure or did not receive the May 5 Cordon Suckering newsletter, then please contact me. Remember that adjusting crop levels later in the season is much easier on cordon-suckered vines. MOVABLE CATCH WIRES (MCW's): For those growers using MCW's on VSP and S-D trained vines, the moving of wires is typically done one to two weeks after bloom. The key is to have shoots long enough to be held in place by the wires. A good indication of this time is at the first sign of cane drop. For mature Cabernet Sauvignon and Merlot vines on north-south rows, we are again recommending moving only the east wire up, leaving the west wire down. This is especially true in blocks where growth has been successfully controlled by good water management. The objective is to reduce hyper exposure and damage to clusters facing the afternoon sun. When moving the downward wire on a S-D, cane flexibility is a determining factor. Growers must determine by trial and error when shoots are flexible enough to be bent without breaking a high percentage of them. Positioning the wire over the shoots and not attaching, just letting the weight of the wire work for you for a week or so will help hold the shoots out vertical, slightly conditioning them and reducing shoot breakage. For VSP blocks being converted to S-D, this process may require a few more days to gradually bend the canes over. LEAF REMOVAL: The objective of leaf removal is similar to cordon suckering, that is to open the canopy for improved light and spray penetration. This operation should follow immediately after moving catch wires, or about two weeks after bloom. This timing reduces the danger of sunburn. Leafing should be restricted to the east side of north-south rows. For east-west rows, the primary focus is on the north side, but some south-side leaves should also be removed in more vigorous areas. Leaves should be removed from only around clusters, and 100% exposure is not necessary. Prior to leaf removal, growers should assess the overall density of their canopies block by block. Where vigor is low or has been successfully managed by regulated deficit irrigation, leafing should be minimal and restricted only to vigorous vines (e.g. end vines and outside rows). If vigor is high, leaf removal should be more aggressive. However, overly aggressive leaf removal can delay fruit ripening. If you have questions, please contact me.