Strawberry harvest is winding down in most locations. Hot weather really pushed what started as a late season so that it is ending ‘right on time’. Renovation is the key activity now. See more on this below. Check fields for evidence of black vine weevil or strawberry root weevil feeding (notching on margins of the leaves) and take steps to control this insect before mowing for renovation. Highbush Blueberries are ripening and harvest should begin soon. Lowbush should be following soon behind. Blueberry maggot fly is active now. Also check for canker diseases (Phomopsis and Fusicoccum). Summer raspberries are also ripening with harvest started this week on early varieties. Yield looks to be down for most growers as a result of widespread winter injury. Check for sap beetle, two-spotted spider mite, Japanese beetle and potato leaf hopper. Cane diseases will also be evident now. Grapes are post-bloom and canopy management activities are in full swing. Past issues of Berry Notes have discusses these practices. Yield on table and juice varieties appears to be down due to winter damage. Wine varieties are looking better. Continue scouting for grape berry moth and mites. Japanese beetles are very active now. Maintain a good post bloom disease management program to avoid late season problems.

Strawberry Renovation – Sonia Schloemann, UMass Extension

Strawberry plantings grown in the traditional matted row system should be renovated after harvest for a number of reasons. These include 1) to reestablish narrow rows, 2) rejuvenate the canopy, 3) interrupt disease buildup, 4) knock down insect and mite populations, 5) allow for effective weed control, and 6) stimulate runner production. For best results, renovation should be started immediately after the harvest is completed. Ideally, individual fields or varieties should be renovated when picking is complete rather than waiting until all fields are ready. The following steps describe renovation of commercial strawberry fields.

Controlling Weeds, Part I: Annual broadleaf weeds can be controlled with 2,4-D Formula 40 at 2 to 3 pts./acre in 25-50 gallons of water applied immediately after harvest. Formula 40 is the ONLY 2,4-D formulation labeled for use in strawberries. The other amine formulations such as Weedar 64 or Amine 4 have a different formulation and are not labeled specifically for strawberries. If grasses are a problem, sethoxydim (Poast) will control annual and some perennial grasses. But do not tank mix Poast and 2,4-D.

Mowing: Mow the old leaves off a couple of inches above the crowns 3-5 days after herbicide application. Take care, espcially in uneven fields, not to mow so low that you damage some of the crowns.

Fertilizing: Fertilize the planting with 20 - 40 lbs./acre of Nitrogen, depending on soil type and organic matter content. A soil test earlier in the season will help guide you on the amount of N to apply. This will also help determine phosphorus and potassium needs. Following up with a leaf tissue analysis in August will help evaluate the adequacy of you fertilization program. A second Nitrogen application should be made in August to complete the N requirement of the plants and support fruit bud initiation.

Narrowing rows: Narrowing row width is important since the rows have a tendency to spread out over time. Wide rows lead to low productivity and increased disease pressure. Narrow rows will give better sunlight penetration, better disease control due to improved air circulation, and better overall fruit quality. Also, more berries are produced at row edges than in the middle. The desirable row width at full canopy is 12-18 inches. This means that rows can be narrowed to as little as 6 inches during renovation. This can be done using a roto-tiller, rotovator, multivaror or various cultivators. Contact you Extension Specialist, equipment dealer or another strawberry grower for advice on the various implements.

Cultivation: Work in straw between rows and throw a small amount of soil over the row by cultivation. Strawberry crowns continue development at the top, and new roots are initiated above old roots on the crown, so 1/2 - 1 inches of soil should be cast over the rows to help with rooting. This also helps cover straw in the row and provides a good rooting medium for the new runner plants.

Subsoiling: Soil compaction can result from tractor use and picker traffic in the field, especially on heavy, wet soils. Subsoiling between rows will help break up compacted layers and provide better infiltration of water. Subsoiling is best done late in the renovation sequence since straw and crop residue can interfere.

Controlling Weeds, Part II: Pre-emergence weed control should begin immediately after all cultivation and subsoiling is complete. Sinbar, Dacthal, or Devrinol are suggested materials. Check the product labels carefully. Devrinol must be incorporated by irrigation, rainfall, or cultivation to be effective. Rate and timing of Sinbar application is critical. If regrowth has started at all, significant damage may result. Again, read and follow the label recommendations carefully with all of these products.

Irrigation: Water is needed for both activation of herbicides and for plant growth. This is easy to forget when multiple crops are grown. All the previous steps can be compromised if this step is not taken. Don’t let the plants go into stress. Ideally, the planting should receive 1 to1-1/2 inches of water per week from either rain or irrigation.

Following are weed management suggestions for strawberry plantings at renovation. Emerged broadleaf weeds can be controlled with 2,4-D (Formula 40) at 2 to 3 pts./acre applied immediately after the last harvest. Formula 40 is the ONLY 2,4-D formulation labeled for use in strawberries. Be extremely careful to avoid drift when applying 2,4-D. If this application is delayed, some damage to strawberries is also possible. Read and understand the label completely before applying Formula 40. If grasses are present at this time, sethoxydim (Poast) will control both annual and some perennial grasses. However, do not tank mix Poast and 2,4-D. Check the product label for rates and especially for precautions. 3-5 days after the 2,4-D application, strawberry plants should be mowed.

Preemergence weed control should begin immediately after the plants are mowed and the soil is tilled to narrow the crop row. The most common practice at this time is to apply half the annual rate of terbacil (Sinbar at 4 oz/acre). It is essential that the strawberry plants are mowed, even if 2,4-D was not applied, to avoid injury from Sinbar. If regrowth of the strawberry plants has started, significant damage may result. Some varieties are more sensitive to Sinbar than others. If unsure, make a test application to a small area before treating the entire planting. Sinbar should not be used on soils with low organic matter, or on reportedly sensitive varieties such as Guardian, Darrow, Tribute, Tristar and possibly Honeoye. Injury is usually the result of too high a rate or overlapping of the spray pattern. If Sinbar is not used, napropamide (Devrinol at 4 lb/acre) or DCPA (Dacthal at 8-12 lb/acre) should be applied at this time. Dacthal is preferred over Devrinol if the planting is weak. If Sinbar is used, napropamide (Devrinol at 4 lb/acre) should be applied 4 to 6 weeks later. This later application of Devrinol will control most winter annual weeds which begin to germinate in late August or early September. Devrinol should be applied prior to rainfall or it must be irrigated into the soil. During the summer, Poast can be used to control emerged grasses. Cultivation is also common during the summer months. Cultivations should be shallow and timely (weeds should be small) to avoid root damage to the strawberry planting. The growth of strawberry daughter plants will also limit the amount of cultivation possible especially near the crop row.

Dacthal is again available for use in strawberries with the same label directions as on the previous label. This is good news for strawberry growers since Dacthal is the only herbicide registered for newly-planted strawberries. Dacthal is now being manufactured by AMVAC.

Understanding the Strawberry at Renovation - Pam Fisher, OMAFRA

Here are three basic concepts in plant physiology that relate to how the strawberry responds to management practices at renovation.

Source sink concept: Strawberry plant parts, such as leaves, roots, crowns, runners, flowers and fruit act as energy providers, (source) or energy users (sinks). Some parts, (i.e. crowns) may be switch for being energy users to energy providers, depending on the time of year.

Competition for energy can occur between plants and within plants. When plants are too close together, they compete with each other for resources. You can expect yield per plant, and average berry size, to be reduced. In a matted row system, optimum plant density is somewhere around 6-8 plants per square foot of row. This is just a ballpark number and depends on variety, soil type, etc.

Competition for resources within the plant occurs too. For example, flowering and fruiting processes compete with runner development. Runner development can compete with crown formation. Crowns can compete with each other. As a result, older, multi-crowned plants tend to produce smaller fruit. The optimum number of crowns in a strawberry plant is different for different cultivars. Growers using the plasticulture system usually aim for 4-6 crowns per plant.

During renovation of matted row plantings, growers use various methods to adjust plant density. Narrowing the rows back to 8-12 inches is the most common practice. Yields can be increased if narrower rows are combined with closer row spacings. The stand may be thinned during mowing or a light raking, which removes weakly rooted plants. Rows can be narrowed to one side so that original mother plants are eventually cut out. Or, a cultivator tooth can be used to cut out older plants in the middle of the row.

Root physiology: Strawberry plants must produce new roots to remain productive. Primary roots penetrate the soil and anchor the plant. Fibrous secondary roots form on the primary roots. These white roots mine the soil for nutrients and water and are frequently regenerated in a healthy plant.

The root system of a strawberry plant is similar to that of an African violet. As the plant grows taller, it initiates new leaves. Older leaves at the base of the plant drop off. New primary roots develop where the old leaves fall off. These roots will not elongate unless they are in contact with moist soil. Root formation tends to take place when the plant is non-fruiting, and when soil temperatures are cool.

Renovation can encourage new root development if rows are narrowed with a rototiller and a small amount (1⁄2 inch) of soil is added to the middle of the row. This encourages new roots to form at the base of the crown. Otherwise, as the plant grows older, the crown extends upward, grows out of the soil, fails to develop new roots, and is more exposed to winter injury.

Environmental interactions: In most June-bearing cultivars, cooler temperatures and shorter day lengths cause the plant to initiate flower buds for next year's crop. Different cultivars respond differently to these environmental triggers. Defining the exact conditions that cause fruit bud initiation to occur is like shooting at a moving target. It is generally believed the process begins as daylengths shorten to less than 14 hours. Short days (less than 14 hours) begin around August 7 in Harrow and August 15 in Ottawa. Flower initiation probably continues until cold temperatures cause plants to go dormant.

These factors affect the timing of renovation practices. It is important to have a vigourous healthy plant in place when flower bud initiation begins. Nitrogen is often applied in early August to give plants a boost. Herbicides such as 2,4-D and Lontrel are not recommended after mid-August because we assume these interfere with flower bud initiation. In northern regions, where summer days are longer, and frost comes earlier, growers may choose not to mow off strawberry plants as part of the renovation process. Mowing can be helpful in terms of reducing pest populations and encouraging new vegetative growth. It is not essential however, and should not be done if plants don't have time to grow back by mid-August.

Plant physiology affects renovation practices in many ways. Growers who understand strawberry plant physiology can use this knowledge at renovation time and manipulate their plants to produce better crops. (Source: The All Ontario Berry Grower Vol. 00, No. 2, June 2001)

Field Update from New Jersey – Gary Pavlis, Rutgers University

Visits this week to numerous fields once again revealed many outbreaks of Phomopsis especially in fields that have not been sprayed with lime sulfur. I realize that this material is a bear to work with and can take the paint right off a tractor, but I am convinced that this industry needs to move back to annual applications. Watch this newsletter for proper timing.

A Phomopsis Canker appears as an elongated, flattened canker. An infected stem feels flattened. Older cankers are covered by small, pimple-like pycnidia which contain spores. Splashing rain or irrigation spreads the spores. In the early stages of canker formation, current year stems may have 1 to 2 inch-long reddish-brownish areas. These areas are the beginning symptoms of Phomopsis Canker. After the stems have been infected for a season, they will wilt during the summer months. (We used to call this winter damage back in the days when we had bad winters.) Under severe disease conditions it is common to see bushes with a half dozen or more wilting stems.

The infectious spores are spread each time rain occurs during the growing season from bud-break through about August 1. Winter injury, spring frost and mechanical harvester injury afford an entry point for infection. Suspect this disease if single canes suddenly die while the rest of the plant remains healthy.

The hot muggy days and the recent rain have caused a little development of the sticky salmon colored anthracnose mold on some overripe berries. This disease could still become bad. To prevent it use Captan in the insecticide sprays.

There have been a few questions regarding nut sedge problems in a few fields. It is usually quite difficult to control it 100%. Solicam at the maximum rate will suppress it but it will not totally clean it up. Sinbar also does a good job if applied at the maximum rate but this is only possible on high organic matter (O.M.) soils. Application is made as late as possible because nut sedge germinates about May 1. A combination of both Solicam and Sinbar will result in early suppression by Sinbar until July 4^th and then Solicam will kick in. In the end, control still won't be 100%. Of course, none of this will help you much this year, but if you have a problem now, you'll have it next year so keep this information handy. (Source: The Blueberry Bulletin, Volume 17, No. 11, June 29, 2001)

Time for Leaf and Soil Samples - David Yarborough, University of Maine

Leaf samples should be taken at the tip-dieback stage of blueberry growth (around the 4^th of July) on prune fields in order to determine your fertilizer needs for the next crop cycle. For a single sample, cut three stems from 30 clones and place them in a paper bag with holes. Keep the samples in a warm dry spot with the top of the bag open to promote drying. Mail the sample to the University of Maine Analytical Lab, 5722 Deering Hall, Orono, ME 04469-5722. The cost of the analysis is $21 per sample unless you strip the leaves from the stems, then it is $18 per sample.

Standard soil nutrient levels for nutrients may not be used to determine optimum wild blueberry production, leaf samples must be taken for nutrient analysis. Soil sampling helps determine soil pH. Ideal soil pH is about 4.8. When the pH is within this range, the nutrients needed for wild blueberry growth are available in proper amounts. When pH is below 4.3 you need to add lime to bring the pH up to 4.8; when pH is above 5.3 add sulfur to bring the pH down. Sample only from the top 3” (including the surface organic pad layer) of soil. (Source: Wild Blueberry Newsletter, June 2000)

Fire Blight on Raspberries– Pam Fisher, OMAFRA

To avoid fire blight, do not plant susceptible varieties such as Boyne and K81-6.

Avoid overhead irrigation on susceptible varieties, because this practice can cause wounding of tissue, favoring infection, and spread the bacteria to healthy plants

Infected canes should be pruned out and removed from the planting as soon as they are observed. Remove infected canes on a dry day to prevent the bacterial from spreading to other canes. Cut the canes out as close to the ground as possible and destroy them. If possible avoid carrying the exposed disease canes through the field.

Insects with piercing sucking mouthparts, such as tarnished plant bugs, can spread the fire blight bacteria and encourage infection. Insects that pierce plant tissue, such as earwigs, can also spread the disease. Ants are efficient at spreading the bacteria to healthy blossoms. Monitor for these insects and control them if necessary.

Table 1: Relative resistance of raspberry varieties to cane infection by fire blight based on laboratory tests.

Resistant	Partially Resistant	Susceptible	Highly Susceptible
Heritage	Ruby	Kilarney	Carnival
Nova	Avon	Comox	Boyne
Royalty	Polana	Taylor	Reveille
	K81-5*	Algonquin	Latham
	Caroline	Canby	Encore

Source: G. Braun, A. Jamieson and P. Hildebrand, Agriculture and Agri-Food Canada, Kentville, N.S. 1999

*Although K81-6 is partially resistant in lab tests, it is very susceptible to fire blight in the field.

(Source: The All Ontario Berry Grower, Volume #00.6 - June 2000)

Grapes

Integrated Pest Management– Tim Weigle, Lake Erie Regional Grape Program/Cornell University

Wiith the estimated reduction in crop size this year there are already questions on what practices can be eliminated to reduce costs. The place I would suggest is the category of practices that I hear growers refer to as 'cheap insurance'. This category includes items like applying another shot of nitrogen, adding an insecticide to the tank because I'm going through anyway, using spray adjuvants not required by the label, etc.

Take the time to review your growing practices. How many times are you investing in 'cheap insurance' throughout the year? Cut practices that have not been shown to improve vine health or yield.

The reason I am going in this direction today is I have heard growers are looking at cutting costs by eliminating the second post bloom fungicide application. Research has shown that the immediate prebloom and postbloom sprays are the two most important disease management applications that can be made. These two sprays should form the base of your disease management program. Then you need to take into consideration the many factors that determine the need for additional fungicide applications, either before or after the bloom period.

Look at a vineyards records (or try to remember its history) to determine disease problems from years past. Last year we ran into a problem with black rot in numerous vineyards across the belt when a second postbloom application was not applied. Concord and Niagara berries are still susceptible to infection by black rot and vineyards with a black rot problem last year or a history of problems with this disease should have a second postbloom fungicide application made.

Berry infections by powdery mildew should no longer be a concern for Concord and other native varieties as they become resistant approximately two weeks after bloom.

Downy Mildew - After fruit set, primary inoculum that causes primary infections should be spent. Secondary infections from existing lesions, however still spread rapidly and explosively. If you have good control up to this point, then Downy may not develop further, with a lot of 'ifs' - including weather, your neighbor, and the disease susceptibility of your variety. Keep on scouting and be ready to react if necessary.

Powdery - Concords and other natives become resistant to new cluster infection about 2 wk. after bloom. Clusters of sensitive hybrid and vinifera varieties remain susceptible for 4 wks. after bloom (and possibly longer for inconspicuous infections). (Source: Lake Erie Regional Grape Program Crop Update, July 3, 2001)

I Have a Light Concord Crop- What Do I Do Now?– Barry Shaffer, Lake Erie Regional Grape Program

Many growers will be facing below average Concord yields this fall. What can growers do now at this time in the growing season to reduce costs and manage taxable income?

1. Estimate your overall crop size. Reports indicate that other varieties did not exhibit the poor set seen in many Concord blocks. Your overall operation may not be so bad after all.

2. Forgo additional N fertilizer. If you split N applications and have not applied your second dose of N, SAVE YOUR MONEY AND DO NOT APPLY N.

3. Most of your crop expenses have already occurred. Many farms in the Lake Erie Grape Farm Cost Survey (LEGFCS) do not vary much from year to year.

4. Scout your vineyards for pests and only apply insecticides if the pest population meets economic thresholds. I would look at additional fungicide applications for problem areas and/or blocks that will be picked towards the end of harvest.

5. Use sulfur for powdery mildew management on sulfur-tolerant varieties such as Niagara, Catawba, and Elvira.

6. Cash market growers may want to go easy on fall pruning and roll most pruning costs into 2002 when, hopefully, the crop will be larger.

7. Spend time in your nonbearing vineyards; the sooner they can be brought into production the better. Neglecting young vineyards will cost you more in lost production then any short-term savings.

8. Capital purchases could be deferred to 2002. Conversely, better deals may be had during low crop years.

9. If you do make capital purchases in 2001, think twice about using Sec. 179. Talk to your tax professional about the options available to you.

10. Talk to your lender now if you are concerned about loan repayments due after harvest. Your lender is apt to have more time to devote to your situation now than after harvest.

11. Keep up your equipment maintenance schedule. This is not the year to suffer from avoidable repair bills! (Source: Lake Erie Regional Grape Program Crop Update, July 3, 2001)

General

Phosphorus management in Michigan fruit crops - Eric Hanson, Michigan State University

Not all Michigan fruit crops respond to phosphorus (P) fertilization. As a general rule, tree crops and grapevines are the least likely to respond to P additions, and blueberries, strawberries and raspberries are the most responsive. Growers need to know how to recognize a P need and when applications are likely to pay. Unnecessary applications waste money and can increase the potential for pollution of surface water.

A typical agricultural soil might contain 1000 lb P/acre in the top six inches, but less than one percent of this may be in soil solution and available to plants at any time. The vast majority of P in soils is a component of organic matter and various minerals. These fractions serve as a slowly available P reservoir that replenishes solution levels. Plants absorb P from solution as either H2PO4- (dominant species when pH is less than 7.2) and HPO4-2 (dominant at pH greater than 7.2), although H2PO4- is preferred. The amount of P in solution is determined to a large extent by the nature and solubility of the P containing compounds in the soil. Soil solution P concentrations between 0.1 and 0.3 ppm P appear necessary for optimum production of crops, although this likely varies by species and stage of development. Fertilizer P added to soils undergoes various adsorption, absorption and precipitation reactions with soil components. The end result is that most fertilizer P adds to the soil reserves, and solution P levels are increased only slightly.

Soil pH has a considerable effect on P fixation and availability. Adsorption of P on iron and aluminum oxides limits solution P concentrations in acidic soils. Adsorption on calcium and magnesium minerals often reduces P availability in alkaline soils. As a result, P availability is generally optimized, and deficiencies are unlikely, if pH is near or slightly below 7.0.

Phosphorus fertilizers

Most P fertilizers are derived from phosphate rock (PR). Since PR is relatively insoluble, it is usually treated with either acid or heat to increase the solubility and availability of the phosphate to plants. The P content of fertilizers is expressed as percent P2O5. Ordinary superphosphate (OSP), triple superphosphate (TSP), are common phosphorus fertilizers derived from the acid treated PR. OSP contains 16-22 percent P2O5, of which 90 percent is water soluble, whereas TSP is higher is analysis (44-52% P2O5) and more soluble (95-98% water soluble). These P fertilizers are typically applied as blended fertilizers that also contain nitrogen and potassium.

For blueberries, mono-ammonium phosphate (MAP) and di-ammonium phosphate (DAP) are also good sources of both nitrogen and P. These fertilizers are very acidic, which often benefits acid-loving plants like blueberries. Plants also seem to absorb P more readily when it is applied in combination with nitrogen.

Determining P needs

The classic symptom of P shortage common to most fruit plants is uniform dark green to purple leaf color. With apples and pears, this color is most apparent in or near the main veins. Leaves are also smaller. In stone fruit crops, the dark green color may turn bronze or reddish purple. Petioles may turn red and older leaves may drop prematurely. Grapevines starved of P experimentally develop small dark green leaves, but deficiencies have not been observed in the field.

Although P deficiency is very rare in deciduous fruit trees, some orchards on very low P volcanic soils in the Pacific Northwest have exhibited deficiency symptoms, which included abnormally early fall color development on leaves. Strawberry and raspberry leaves turn dark green to purple, with the first symptoms developing on the older leaves. Deficient blueberry plants may be stunted, with dark green leaves and narrow, reddish twigs.

Tissue analysis is valuable in diagnosing P shortages. Tissue P levels considered deficient are less than 0.07 percent in blueberries, 0.2 percent in strawberries (newly expanded leaves) and raspberries, 0.1 percent in stone fruit, 0.12 percent in apples and pears, and 0.15 percent in grapes (petioles). If tissue samples are collected earlier than the recommended time in late July to early August, P levels may be higher than normal and these deficiency levels will not apply.

Soil tests provide a reasonable guide for P fertilizer needs for strawberries and raspberries, but not for blueberries, tree fruits or grapevines. Prior to planting any of these crops, soil P levels should be above 100 ppm. However, in established orchards, vineyards and blueberry plantings, soils levels below 100 ppm do not indicate a P deficiency. Soil test levels tell little about whether these plants will respond to added P.

Applying phosphorus

The most critical time to apply P is prior to planting. Phosphorus is nearly immobile in soils, so this is the only time to increase levels throughout the root zone of perennial crops. Thoroughly sample the soil before planting and incorporate P, as recommended based on the soil test results, along with needed lime and potassium. Preplant applications will usually provide adequate P for a several years (strawberries, raspberries) or even for the life of the planting in the case of orchards and vineyards.

In established fruit plantings, apply blended fertilizers containing P if tissue analysis or symptoms indicate a need. These materials should be applied when the nitrogen fertilizer is normally applied.

Why orchards and vineyards typically do not respond to P applications is not clear. Perhaps the roots of trees and grapevines mine enough soil to obtain sufficient P even when levels in the topsoil are marginal. These plants also form symbiotic associations with specific soil fungi (mycorrhizal fungi), and these relationships may also help the plants extract adequate P even from infertile soils. In some instances, P applications may be justified to maintain a healthy vigorous sod in fruit plantings. (Source: Michigan State University’s Fruit Crop Advisory Team Alert, Vol. 16, No. 9, June 5, 2001)

Massachusetts Berry Notes is a publication of the University of Massachusetts Extension Fruit Program which provides research based information on integrated management of soils, crops, pests and marketing on Massachusetts Farms. No product endorsements over like products are intended or implied.

Crop Conditions and Pest Summary

Strawberry

Strawberry Renovation – Sonia Schloemann, UMass Extension

Understanding the Strawberry at Renovation - Pam Fisher, OMAFRA

Highbush Blueberry

Field Update from New Jersey – Gary Pavlis, Rutgers University

Lowbush Blueberries:

Time for Leaf and Soil Samples - David Yarborough, University of Maine

Brambles

Fire Blight on Raspberries– Pam Fisher, OMAFRA

Grapes

I Have a Light Concord Crop- What Do I Do Now?– Barry Shaffer, Lake Erie Regional Grape Program

General

Phosphorus management in Michigan fruit crops - Eric Hanson, Michigan State University