Wisconsin Fruit News
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Wisconsin Fruit News Volume 1 Issue 9 – August 5, 2016 In This Issue: Events this Week General Information: August 10, 2016 – Cranberry Growers Summer Field Day Plant Disease Diagnostic Clinic Brockway Cranberry, Black River Falls, WI page 1 Insect Diagnostic Lab update August 15, 2016 – Urban Horticulture Day page 2 10 am – 2 pm; West Madison Agricultural Research Station, Verona, WI Berry Crops: Leaf tissue analysis for berry crops General Information page 3 UW-Madison/Extension Plant Disease Diagnostic Clinic (PDDC) update Blueberry stem gall wasp By: Brian Hudelson, Sean Toporek, and Ann Joy page 4 The PDDC receives samples of many plant and soil samples from around the state. Cranberries: The following diseases/disorders have been identified at the PDDC from July 23, 2016 Cranberry degree-day update through August 1, 2016. page 6 PLANT DISEASE/ PATHOGEN COUNTY Grapes: DISORDER Grape disease update page 8 Apple Cork Spot None Oneida Grape insect scouting report Cedar-Apple Rust Gymnosporangium sp. Dane, Eau page 11 Claire Grape developmental stages Chemical Burn None Dane page 11 Root Rot Phytophthora sp., Shawano Pythium sp. Tree Fruits: Reduced risk insecticide: Movento Blackberry Botryosphaeria Botryosphaeria sp. Rock page 15 Cane Canker Antique apples with modern value Septoria Leaf Spot Septoria rubi Taylor page 16 Pear Entomosporium Entomosporium sp. Oneida Update on brown marmorated Leaf Spot stink bug page 17 Chemical Burn None Dane Raspberry Calendar of Events: Anthracnose Sphaceloma necator Sheboygan page 19 Raspberry Leaf Cylindrosporium rubi Price Spot Verticillium Wilt Verticillium sp. Sheboygan For additional information on plant diseases and their control, visit the PDDC website at pddc.wisc.edu. 1 UW-Madison/Extension Insect Diagnostic Lab update By: PJ Liesch The following insects were reported to the Insect Diagnostic Lab (IDL) as being active in the state between July 22nd and Aug 4th, and have the potential to impact fruit production in the region. If you would like more information about the UW Insect Diagnostic Lab, you can visit our website. -Japanese Beetles are out in full force and will continue to be present for several weeks. Of interest for growers in the northern part of the state is a report from the Spooner area in Washburn County. Japanese beetles are abundant in the southern portions of the state, and this detection in Washburn County is one of the northern-most detections in Wisconsin. Most of the reports of fruit damage at the UW Insect Diagnostic Lab have been on raspberries, grapes, and apples. -Brown Marmorated Stink Bug nymphs continue to be spotted in Dane county and a single nymph was recently spotted on the east side of Madison, several miles from earlier reports. Growers should be on the lookout for juveniles and adults in the coming weeks. For more information about monitoring for brown marmorated stink bug in Wisconsin, please see the article on pages 17-18 of this issue of the newsletter. -Second generation codling moths are active and growers with pheromone traps will be able to monitor for their activity. A number of reports of codling moth damage from first generation caterpillars have come in from backyard growers in the state. -Spotted Wing Drosophila reports have started to trickle in to the UW Insect Diagnostic Lab. Growers of berry crops, especially raspberries and blackberries should be keeping an eye out for this pest. We have addressed spotted wing drosophila monitoring and control many times in pervious issues of this newsletter: for information on chemical controls, please see Issue 5, pages 4-5; for information on exclusion control with high tunnels, please see Issue 6, pages 3-6; and for information about which raspberry varieties are least susceptible to spotted wing drosophila, please see Issue 4, pages 3-6. The following insect was previously reported to the Insect Diagnostic Lab (IDL), as being active in the state between July 8th and July 21st: -Grape Phylloxera has been confirmed on several grape samples sent in to the IDL. Important considerations for phylloxera include variety/rootstock selection. For more information on grape phylloxera, please refer to the Grape section of previous issues of this newsletter, for example Volume 1, Issue 6, page 18. 2 Berry Crops Leaf tissue analysis for berry crops - now is the time By: Amaya Atucha, UW-Extension State Fruit Specialist Leaf tissue analysis is the best indicator of plants’ nutritional status as it measures directly the concentration of nutrients in the plant. Soil testing can be a useful tool as well; however, results of a soil test do not always correlate with the amount of nutrients that plants are actually up-taking. A good recommendation for growers is to take foliar samples on an annual basis and a soil test every 3 years. Foliar nutrient analysis is the best way to assess the effectiveness of your fertility program, as it allows growers to detect when nutrient levels in the plant are approaching deficiencies, before visual symptoms are observed, and allowing growers to take corrective action in advance. The analysis provides information on N, P, K, Ca, Mg, Fe, B, Mn, and Zn levels in leaves sampled, and a guideline with the concentration range for these nutrients expected in healthy plants. When and how should I collect the leaf samples? The standard recommendation for foliar sample collection is mid-summer because during this time of the year nutrient levels are most stable in the plants. For blueberries, 80 to 100 leaves should be collected from the middle section of shoots (not old leaves from the base, nor new leaves from the tip), selecting newly matured leaves that are fully exposed to the sun. For blackberries and raspberries, collect a minimum of 50 fully expanded leaves from primocanes (non-fruiting canes). For strawberries a minimum of 50 leaves should be collected from the first fully expanded leaves after renovation. A general recommendation is to collect the leaves across the planting in a zigzag pattern. For the main sample, leaves should be sampled from plants that are representative of the entire field, but separate samples should be collected from areas where plants have poor growth or present visual symptoms of nutrient deficiencies. Once you have collected the leaves, gently wash them with distilled water to rinse off soil and spray residues, and let them air dry. Place the leaves in a clearly labeled paper bag and send them to the lab. If you cannot wash the leaves after collecting them, place them in a cooler or refrigerator until you can process them (do not allow leaves to wilt before you wash them). As a reference, we have provided tables below with the desired range of nutrient concentrations for blueberries, caneberries, and strawberries. Critical nutrient foliar concentration for Blueberry (source: Penn State University): Element Deficient Below Normal Above Excessive Normal Normal N (%) 1.65 1.7 1.9 2.1 >2.1 P (%) 0.05 0.06 0.1 0.18 >0.18 K (%) 0.35 0.4 0.55 0.65 >0.65 Ca (%) 0.35 0.4 0.6 0.8 >0.80 Mg (%) 0.18 0.2 0.25 0.3 >0.30 Mn (ppm) 45 50 250 500 >500 Fe (ppm) 65 70 200 300 >300 Cu (ppm) 4 5 11 15 >15 B (ppm) 29 30 40 50 >50 Zn (ppm) 14 15 25 30 >30 3 Critical nutrient foliar concentration for Brambles (source: Cornell University): Element Deficient Below Normal Above Excessive Normal Normal N (%) 1.80 2.00 2.50 3.00 >3.00 P (%) 0.23 0.25 0.35 0.40 >0.40 K (%) 1.45 1.50 2.00 2.50 >2.50 Ca (%) 0.57 0.60 1.70 2.50 >2.50 Mg (%) 0.27 0.30 0.70 0.90 >0.90 Mn (ppm) 45 50 150 200 >200 Fe (ppm) 48 50 150 200 >200 Cu (ppm) 6 7 30 50 >50 B (ppm) 28 30 40 50 >50 Zn (ppm) 18 20 35 50 >50 Critical nutrient foliar concentration for Strawberries (source: Cornell University): Element Deficient Below Normal Above Excessive Normal Normal N (%) 1.50 1.80 2.00 2.80 >2.80 P (%) 0.20 0.25 0.35 0.40 >0.40 K (%) 1.20 1.50 2.00 2.50 >2.50 Ca (%) 0.60 0.70 1.50 1.70 >1.70 Mg (%) 0.25 0.30 0.45 0.50 >0.50 Mn (ppm) 40 50 150 250 >250 Fe (ppm) 50 60 150 250 >250 Cu (ppm) 5 7 10 20 >20 B (ppm) 20 30 60 70 >70 Zn (ppm) 15 20 35 50 >50 Blueberry stem gall wasp By: Janet van Zoeren and Christelle Guédot, UW- Extension, Entomology The blueberry stem gall wasp is a secondary pest of blueberry, and on most Wisconsin farms has not been a significant problem in the past. However, over the past few years, numbers of this pest have been rising in Michigan, so it’s a good idea to be aware of it this growing season, to monitor for the galls and to learn how to best manage it if the need arises. Identification and damage symptoms: The blueberry stem gall is a kidney-shaped or spherical growth 1-2 inches in diameter formed on the stem of the blueberry plant, following the infestation by the blueberry stem gall wasp. Initially, the gall is a reddish-green color, and it turns grey-brown by fall. The wasp causing this damage is tiny, being no more than 1/10th of an inch long (see picture at right). These wasps are native to North America, and attack cultivated and wild, low- and high-bush blueberries.