In this issue
Tree fruit news
§ Summer leafroller control: Scouting will save you money!
Small fruit news
§ Options for organic management of blueberry maggot
§ Time to renovate strawberries
Other news
§
§ MSU Student Organic Farm field days
§ Regional reports
§ Weather news
Larry Gut, David Epstein and John Wise
Entomology
The availability of several excellent obliquebanded leafroller control materials has growers asking advice for proper timing and sequencing of these materials, but before insecticide applications are undertaken, growers are best advised to first determine whether such applications are necessary. Due to the difficulty in scouting for overwintered obliquebanded leafroller larvae in early spring, obliquebanded leafroller insecticides are routinely recommended as part of an early spring spray program on farms with historical leafroller damage. As larvae mature in late spring, though, their presence is far easier to detect, and visual inspections for larvae or signs of their presence can save growers the cost of unnecessary, and often expensive, summertime insecticide applications. In other words, a key piece of information growers need to make a good economical decision for summer leafroller control is the extent to which larvae survived the early season treatment. With the excellent control provided by the new compounds registered in recent years, fewer and fewer are surviving.
Moth captures in pheromone traps provide valuable information to the scout and grower, including the establishment of biofix, but are not a reliable indicator of leafroller abundance or potential damage. Obliquebanded leafroller traps have a large active space, potentially catching moths that originate from within the trapped orchard, neighboring or more distant orchards and native habitats. Thus, high moth catches may or may not indicate that the orchard being monitored has a leafroller problem. Very low catches of less than five per week strongly hint that obliquebanded leafroller is not a problem. In either case, assessing larval activity is highly recommended to determine if a treatment is warranted.
Scouting orchards for surviving obliquebanded leafroller larvae in growing terminals is the best way to judge whether intervention in the summer is likely to be needed. Larvae are green with brown to black head capsules and are about 25 mm long when fully grown. Often, a scout will detect signs of leafroller activity rather than the actual larva. The name leafroller comes from the larva’s habit of rolling leaves to form a shelter. These feeding sites are most often found at the tips of growing shoots. Larvae also will use silk webbing to attach two leaves or a leaf and fruit together to form a shelter. The presence of webbing is a good clue that leafrollers are around. Orchards in which less than 2 percent of the terminals were infested should be monitored in the summer, but controls may not be warranted. Higher levels of shoot infestation are cause for concern and control measures are likely needed to prevent fruit injury. This investment of time could result in saving several sprays.
Obliquebanded leafroller
GDD model
|
DD° Base 42 (Post Biofix) |
Event |
Action |
|
Tight cluster |
Majority of larvae have emerged from shelters |
Examine fruit buds for larval activity |
|
0 DD° = biofix |
1st sustained moth captures |
Set DD° = 0 |
|
220-250 DD° |
Peak moth flight - |
|
|
400-450 DD° |
Start of egg hatch |
Timing for scouting-based treatment with larvicides (egg materials applied earlier) |
|
1000 DD° |
End of egg hatch |
|
|
2300 DD° |
Peak moth flight - 2nd generation |
|
|
2750 DD° |
Start of 2nd generation |
Timing for scouting-based treatment |
Degree-day models are essential tools to be used in timing insecticide sprays. Optimal timing for summer sprays varies according to the life stage or stages that are targeted by the product of choice. For conventional insecticides, like organophosphates (OPs), pyrethroids and carbamates, the first sprays should be targeted between 400 and 450 GDD after biofix to control hatching larvae before they can damage fruit. Obliquebanded leafrollers are resistant to OPs in most apple growing regions of the state and are generally not the best option for control. Bt's are most effective when applied during warm weather conditions (daily highs in the 70's). If Bt products are used, the latter timing (450 GDD) may be the better choice because they have a short residual, which must be present to control the larvae at the time and location they are actively feeding. If the first application is applied too early, it may take four or more sprays to keep the active ingredient on the foliage throughout the long period of larval activity. Bt products are generally more effective with a lower tank pH. SpinTor has a similarly short residual (seven to ten days), but provides some contact efficacy, which will help kill larvae as they move to the actively growing terminals. SpinTor is also a good choice for leafroller control in cherry blocks where control with OPs and pyrethroids is failing to provide adequate protection. Proclaim, a new material (Avermectin class) has also shown very good activity against OBLR, and requires ingestion by larvae.
In contrast, if Intrepid is used early it should be targeted to cover obliquebanded leafroller egg masses around 350 GDD post-biofix, so that larvae will consume the chemical as they eat their eggshells upon emergence. Intrepid can also be used later to protect fruit against damage from older larval instars. Upon application, Intrepid has a long residual effect, but should be reapplied where necessary on a 14-day interval to insure coverage of new terminal growth. Good, thorough coverage is key to leafroller control with materials requiring ingestion to be effective. The addition of an agricultural adjuvant to Intrepid 2-F is recommended to improve spray deposition.
Rimon acts by suppressing development within the egg, as well as larvae that consume it. Hatching of eggs laid by treated adults will also be inhibited. Eggs are particularly susceptible to these products when laid on top of sprayed residue, thus sprays should target 100-200 GDD after obliquebanded leafroller biofix. Similarly, Esteem applied at obliquebanded leafroller egg laying timing will also provide some control, though it is more typically used for the overwintering generation.
It should be noted that treating the summer generation of obliquebanded leafroller with SpinTor, Rimon or Proclaim would also provide some control of codling moth, Oriental fruit moth and spotted tentiform leafminer. Intrepid applied at the earlier summer obliquebanded leafroller timing would also assist in controlling codling moth and tufted apple budmoth. Esteem will provide control of San Jose scale crawlers and some added control of codling moth. Bt's can also be expected to control other leafrollers when applied in the summer for obliquebanded leafroller control.
As with many of our key apple pests, obliquebanded
leafroller has a track record of developing resistance to insecticides.
Currently, there are some good options for control of this pest. Practicing
good resistance management should help conserve their efficacy. We encourage
you to rotate materials with different modes of action. For example, if Rimon was the material of choice
for control of overwintering larvae, opt for Proclaim, SpinTor or Intrepid if a
summer treatment is warranted. During periods of warm weather, Bt is an
excellent option and a good resistance management strategy.
Obliquebanded leafroller insecticides
labeled for apples
|
Compound Trade Name |
Chemical Class |
Life-stage Activity |
Optimal Spray Timing for OBLR |
Residual Activity |
Mite Flaring Potential |
|
Guthion, Imidan |
OP’s |
Larvae |
Biofix + 400-450 DD |
10-14 days |
L - M |
|
Lannate, Sevin |
Carbamates |
Larvae |
Biofix + 400-450 DD |
5-7 days |
M - H |
|
Asana, Warrior, Danitol, Decis |
Pyrethroids |
Larvae |
Biofix + 400-450 DD |
7-10 days |
H |
|
Deliver, Dipel, Crymax |
Bt’s |
Larvae |
Biofix + 450 DD |
5-7 days |
L |
|
Spintor, Entrust |
Spinosyn |
Larvae |
Biofix + 400-450 DD |
7-10 days |
L |
|
Rimon |
IGR (chitin inhibitor) |
Eggs, Larvae |
Biofix + 100-200 DD Residue under eggs |
14+ days |
M* |
|
Proclaim |
Avermectin |
Larvae |
Biofix + 400-450 DD |
7-10 days |
L |
|
Intrepid |
IGR (MAC) |
Eggs, Larvae, Adults (sublethal) |
Biofix + 350 DD Residue over eggs |
14+ days |
L |
|
Esteem |
IGR (juvenoid) |
Eggs, Larvae |
Biofix + 100 DD Residue under eggs |
10-14 days |
L |
*
May cause mite flaring in combination with carbaryl or pythrethroids that kill
predacious mites.
Luis Teixeira and Rufus Isaacs
Entomology
The blueberry maggot is a key pest of blueberries because infestation of fruit by the larvae of blueberry maggot makes it unmarketable. Management of this insect, whether organically or conventionally, depends on monitoring and appropriate reaction to trapping of flies. Organic growers may be more likely to engage in cultural controls to disrupt the life cycle, but the goal is the same – to prevent berries from becoming infested. This article reviews the currently available organic management options against blueberry maggot.
The first blueberry maggot flies begin to emerge from the soil in late June or early July, and are often stimulated to emerge by rain. After emergence, flies spend six to ten days feeding on insect honeydew, secretions and other deposits on foliage and bird droppings. During this period, female flies become sexually mature and mate. Once mated, the females seek ripening blueberries in which to lay eggs. At this time, flies often immigrate into fields from surrounding wild habitats, but if infestations are established in fields the flies can emerge here and quickly move to the bushes. The female fly punctures the skin of the blueberry in order to deposit a single white elongate egg. In three to five days, the eggs hatch and the larva (maggot) begins feeding. As the larva feeds and grows, the berry begins to shrivel. Breaking open one of these berries will reveal a small white maggot set against the bluish-colored flesh of the fruit. After two or three weeks of feeding, the larva becomes full-grown and the berry is unmarketable. Infestations tend to increase rapidly to a peak by mid-August when larvae begin exiting the berries and dropping onto the soil. Once there, they burrow into the soil and pupate in the top few inches of soil.
Weekly checking of yellow sticky traps can be used to identify when adult blueberry maggot flies are active, and action should be taken soon thereafter to prevent infestation of the fruit. Yellow traps baited with ammonium odor are the most attractive. The traps can be purchased with a glue impregnated with the odor, and this lasts for about two weeks. After that, yellow plastic “chargers” can be used to provide the odor, so that the traps can be changed when they become filled with insects. To increase the chance of catching flies, hang traps in a V-orientation with the yellow side facing down. Good maintenance of traps will ensure that flies will be attracted to the traps, so it is important to clean traps at each visit and to maintain the odor bait.
Accurate fly identification is critical for blueberry maggot
management because there are a few other species of fruit flies that look
similar to the blueberry maggot. Being sure that a fly on the trap is not a blueberry
maggot can help growers save money by avoiding unnecessary sprays, or make the
appropriate decision to protect the fruit if the fly is a blueberry maggot. In
Cultural controls can be powerful approaches to reducing
infestation by blueberry maggot. Selection of very early- or very late-ripening
varieties may minimize the likelihood that flies will be active when the fruit
is ripening. It will be interesting to see how the adoption of late-season
varieties affects this pest. Research in
Mulches may have direct and indirect effects on blueberry
maggot. If an infestation is established in a field, application of a dense
wood mulch or plastic over the top of the pupae in the fall or in the spring
could trap the flies and reduce their ability to emerge in the following
summer. However, there may also be indirect effects on the natural enemies that
walk across the ground surface searching for larvae or pupae. In experiments
conducted in
Options for chemical control of blueberry maggot under
organic standards in
Kaolin is a naturally occurring clay, resulting from
weathering of aluminous minerals such as feldspar. Kaolin likely acts as an
irritant to the blueberry maggot. After landing on a treated surface, particles
of kaolin break off and attach to the insect’s body triggering intensive
grooming that distracts the flies from laying eggs. Surround® WP Crop
Protectant (Engelhard Corp.) is a kaolin product registered for use in
Neem products are derived from the neem tree, which is
native to southern
Pyrethrum is an insecticide derived from the powdered, dried
flower heads of the pyrethrum daisy, which is native to southwest
Spinosad is composed of spinosyns A and D, substances
produced by aerobic fermentation of a filamentous bacterium found in the soil.
Spinosad acts primarily through ingestion. It activates the nervous system of
the insect, causing loss of muscle control. Spinosad products registered for
control of blueberry maggot in
Growers aiming to protect berries from blueberry maggot infestation should be aware that the residual control provided by these insecticides is generally less than that provided by conventional products. Thus, if blueberry maggot flies continue to be caught on monitoring traps, a weekly spray interval may be more appropriate to maintain protection of berries.
Eric Hanson
Horticulture
Strawberry beds that are to be carried over for another harvest season need to be renovated. Deciding whether to renovate or remove a bed differs with each grower’s circumstances, such as market demand, land availability and production costs. As strawberry fields age, yields and berry size decline, while weeds and some diseases increase. Growers with high market demand but limited available acreage may need to retain beds longer. In the end, an educated decision requires thorough knowledge of your production costs and net returns over the preceding seasons. If you decide to renovate, start as soon as harvest is over. The earlier runner plants develop, the higher they yield the following year, so delaying renovation will reduce yields next year. Also keep in mind that renovated beds need abundant water in July and August. To renovate, follow these steps:
Mow off the leaves just above crown height if the plants are healthy. Mowing may not be desired if the plants are stressed by drought or root diseases because weak plants have difficulty developing new leaves. Also, do not mow the leaves if renovation is delayed for more than a few weeks after the end of harvest.
Narrow the rows to eight to ten inches by cultivating with a rototiller or disk. Rototillers with tines removed above the row work very well because they toss some soil on top of remaining plants, which encourages additional rooting. However, more than an inch may smother the plants.
Some growers have had success narrowing rows by treating the row middles with directed or shielded sprays of the herbicide Gramoxone (paraquat). Gramoxone is a contact weed killer that is not mobile in plants, so it only kills treated tissues. This method effectively narrows the plant row, and does not expose new weed seeds by disturbing the soil. One potential problem with this approach is that it does not provide a loosely tilled soil which is best for the rooting of runner plants. It also does not throw soil back over crowns.
Herbicides.
Renovation is also a useful time to treat broadleaf weeds with amine forms of
2,4-D, such as Amine or Formula 40. Strawberry plants tolerate 2,4-D after
harvest because they are not actively growing. If broadleaf weeds are a
problem, apply 2,4-D a few days before mowing. This herbicide must be absorbed
by the weed leaves to be effective, so don’t mow off the weed leaves before
applying 2,4-D. Sinbar can also be applied at renovation for preemergent weed
control. Apply 3-6 oz of Sinbar 80W per acre, using the lowest rates on sandy
ground or weaker plant stands. Mow plants first so that Sinbar is applied
uniformly to the soil. Irrigate to rinse the herbicide off the plants and into
the soil.
Fertilizing. The last step in renovation is to fertilize. On heavier loamy soils, apply enough fertilizer to supply 50 lb N per acre. On sandy soils, apply 30-40 lb N at renovation and again in early August. Do not neglect irrigation on renovated beds.
Irrigating. Do not neglect watering at renovation and during the remainder of the summer. Runner plants that develop during July and August need adequate moisture to root. The amount of water available to strawberries is the product of the water holding capacity and the rooting depth, usually considered 8-12 inches (Table 1). Irrigate when about half of the available water has been used. During hot weather, this means strawberries may need irrigation every two to three days (sandy soils) to every four to five days (heavier soils).
Table 1. Available water in a strawberry rootzone as affected by soil texture
|
Soil texture |
Available water (inches) |
|
|
Per inch of depth |
In root zone (8-12 inch depth) |
|
|
Loamy sand |
.07 |
.6 - .8 |
|
|
.13 |
1.0 – 1.6 |
|
Loam |
.17 |
1.4 – 2.0 |
|
Silt and clay loams |
.18 |
1.5 – 2.2 |
Lyndon Kelly
Extension Irrigation Educator
MSU Extension/ Purdue Extension
New wells and surface water withdrawals in
or from St. Joseph County MSU Extension at http://www.msue.msu.edu/stjoseph then navigate to the link for irrigation on the left side.
The latitude and longitude coordinates for the location are required for all new large scale withdrawal location. This information may be provided by handheld GPS units or the groundwater mapping website (http://gwmap.rsgis.msu.edu). Many MSU Extension offices or your local Conservation District office can assist with the use of finding the latitude and longitude coordinates. Providing the latitude/longitude location of withdrawals will allow mapping and analysis of effects of withdrawals on groundwater and stream base flow in the watershed basin.
Information at the St. Joseph County
MSU Extension website (http://www.msue.msu.edu/stjoseph)
can assist in estimating water use for irrigation and other agricultural water
uses. Lyndon Kelley, irrigation management educator for MSU Extension can
answer many of the questions related to
An estimate of expected water use by the month is needed. Most irrigators will estimate their water use from experience multiplied by the number of acres irrigated. As an example: 100 acres with 1.5 inches of irrigation applied in June would have an estimated water use of 150 acre inches for the month. Three inches of estimated irrigation needed in both July and August and 1 inch in September, would give an estimated annual water use of 550 acre inches for the year.
The registration process also calls for an estimate of consumptive water use. Consumptive water use is the amount of water that is lost from the area of withdrawal. Since most water pumped for crop irrigation ultimately goes into evapotransporation, the consumptive use is estimated to be high or about 90 percent. Water used for harvest cooling is mostly retuned back to the surface or groundwater so the consumptive use is estimated to be low or about 5 to 10 percent.
The registration process establishes a “baseline capacity” based on the available withdrawal capacity of a system. The baseline capacity of the system should be reported as pump capacity in gal/min along with a pump and system description, which is compatible with the well log. Baseline capacity applies to both wells and surface water withdrawals. Please note: You should report this baseline capacity value on the registration form on the line listed as “rated capacity.”
For further information, water resource specialist, Abigail Eaton of the Michigan Department of Agriculture Environmental Stewardship Division heads up the registration process for large water withdrawals. She can be contacted at 517-241-3933 or eatona@michigan.gov.
Susan Smalley
C.S. Mott Group for Sustainable Food Systems,
The Michigan State University Student Organic Farm with support from the USDA Risk Management Agency is featuring two farm field days this summer to highlight two sustainable production strategies for small scale and limited resource specialty crop farmers.
Hoophouses
and Passive Solar Greenhouses for Protected Cultivation
Tuesday, June 26, 9:00 AM – 4:00 PM
§ This workshop will include:
§ Design options for a range of costs and sizes
§ Construction methods including cold frames and small scale build-your-own
§ Crop selection and scheduling
§ Soil preparation, building soil organic matter and fertility management
§ Planting, growing and harvesting methods (we expect to be harvesting tomatoes)
The workshop is presented by Adam Montri, MSU and MIFFS
Hoophouse Outreach Specialist, and Dr. John Biernbaum, MSU Professor of
Horticulture.
Edible forest gardening: intensive
perennial and annual permaculture
Tuesday, July 10, 2007, 9:00 AM – 4:00 PM
§ The edible forest gardening workshop will include:
§ Introduction to principles of the edible forest garden and permaculture
§ Mimicking a natural forest ecosystem, guilds, three dimensional planning
§ Comparison of a forest, orchard, annual vegetable and mixed polyculture settings
§ MSU Edible Forest Garden Design and Planting, a 0.75 acre diverse planting
§ Selection of perennial tree fruit, nut, small fruit and herbs for the edible forest garden
Presenters for this workshop are Jay Tomczak, MSU Graduate Student and Certified Permaculturalist, and Dr. John Biernbaum, MSU Professor of Horticulture.
Both workshops will take place at the Michigan State
University Student Organic Farm, located at the MSU Horticulture Teaching and
Preregistration is required as enrollment is limited. To register, contact Adam Montri at admontri@anr.msu.edu or 517-432-3381. Also, please bring your own lunch. A walk-in cooler is available to refrigerate lunches. Fresh vegetables and water will be provided.
Mark Longstroth
Bill Shane
Greg Vlaming
Last week was hot with highs near 90F and lows around 60F. There was no rain last week and soil moisture reserves in sandy soils are exhausted. Crop growth has slowed due to the hot, dry conditions. A cold front moved through the region Tuesday morning (June 19) bringing a little rain (0.1-0.3 inches). Soils are still dry. The forecast is for cooler weather with little chance of rain.
|
|
Grapes from |
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
1533 |
1312 |
972 |
874 |
|
|
1622 |
1390 |
1040 |
886 |
|
|
1393 |
1171 |
846 |
766 |
|
Rose chafers are finished. Both Japanese beetle and false Japanese beetle are out. We are also catching blueberry maggot and cherry fruit fly. Japanese beetle and fruit fly should emerge in good numbers if we get rain. Aphid numbers are building. We are catching peach tree borer.
Peaches are at pit hardening, and the fruit are 1.5 inches in diameter. We are still finding Oriental fruit moth larvae feeding in the shoot tips and fruit. The second generation of Oriental fruit moths is emerging in some areas. Peach powdery mildew or rusty spot can be found. There is leaf drop due to bacterial spot.
Tart cherries fruit are red and harvest will begin this weekend. Maintain protection for cherry leaf spot. Growers should monitor cherry fruit fly traps. There is some leaf fall due to bacterial canker and cherry leaf spot.
Sweet cherries harvest of early varieties continues. Eastern cherry fruit fly was caught late last week. Birds are a significant problem. Tuesday’s rain was a brown rot infection event so fungicides controls should be applied.
Apple fruits are 1.25 to 1.5 inches in diameter. Fire blight is a serious problem in some orchards. Windy conditions Monday, June 18 with thunderstorms Tuesday morning can spread fire blight by trauma blight infection. Aphids and leafhoppers can also spread the disease. Codling moth trap catches are up, and we can expect an increase in egg hatch later this week. Eighth inch larvae were found feeding in the fruit. Obliquebanded leafrollers are at peak egg hatch, 600 GDD after biofix. A spike in Oriental fruit moths indicates that the second generation flight is starting. European red mites numbers are building in some orchards and hard to find in others. Aphids are common on actively growing shoots. Growers should treat young nonbearing trees to control potato leafhopper.
Pear fruit are 1.25 inches in diameter. Pear psylla adults are flying.
In blueberries, early varieties
such as
In grapes, Concords are at buckshot
berry and vinifera are at berry shatter.
Strawberry harvest is winding down. The hot dry conditions caused fruit to ripen rapidly and size suffered. Sap beetles are attacking ripe fruit. Growers should prepare for renovation.
In raspberries, summer red raspberry and black raspberries are coloring and harvest should begin soon. Japanese beetles usually emerge with the first ripe fruit and early treatment will discourage feeding.
Cranberries are blooming.
The next Monday Fruit Update
meeting will be Monday June 25, 5:00 PM, at the Fruit Acres Farm in
The next grape IPM scouting meeting will be July 12 at Bob Dongvillo's farm, south of Scottdale; and August 19 at Lemon Creek Vineyards, west of Berrien Springs. These meetings start at 6:00 PM. For more information on these meetings, call Mark Longstroth at (269) 675-8313.
Warm temperatures over the last week certainly have continued the trend of pushing ahead our degree day totals, and more importantly the development of many other fruit crops. Many farms began harvesting sweet cherries over the weekend or early this week, which is one of the earliest beginnings of sweet cherry harvest in the last 30 years that I can remember. For most of our farms, it is an “early sweet cherry season” when they begin harvesting late in June. I expect sour cherry harvest to fall into place rather quickly here, as will summer red raspberry harvest. So, our season is running a bit under a week ahead of normal in terms of degree days, but is almost two weeks ahead of normal in terms of beginning of harvest for many of our fruit crops.
The lack of soil moisture is getting to be of greater concern to fruit growers across the region. With warm temperatures, low relative humidity, and many days with high winds, it has taken a lot of the moisture from our soil. The last major rain event for most fruit growers was June 3 or 4 when many received around one inch of rain. So, where growers are able to irrigate, irrigation systems have been fired up and running almost constantly.
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Commerce ( |
1387 |
1161 |
838 |
|
Emmett (St Clair) |
1323 |
1108 |
802 |
|
|
1421 |
1198 |
851 |
|
Lapeer (Lapeer) |
1365 |
1145 |
834 |
|
|
1505 |
1272 |
938 |
|
Romeo ( |
1524 |
1286 |
942 |
Apples continue
to size quite nicely, with most being around 1.5 inches in diameter in the
We have had a heavy flight of obliquebanded leafrollers, San Jose scale crawlers and the first Japanese beetle catch over the last week, and many insects and diseases are more prevalent than last week. Obliquebanded leafroller trap catches have been high over the last week, with a big flight. Japanese beetle adults have been seen feeding in several blocks of apples across the region. The range of this pest continues to expand. San Jose scale crawlers were seen at several farms across the region beginning late last week. Codling moth adult trap catch is zero in most mating disrupted blocks and numbers are much reduced in conventional blocks. Oriental fruit moth trap catches are near zero; however flagging of apples and peaches has become more evident over the last week. Potato leafhopper adults and nymphs are being seen in higher numbers, particularly newly planted trees which tend to be sprayed less than bearing blocks of apples. Spotted tentiform leafminer leaf mines are showing up on leaves on the insides of many trees, however their numbers are fairly low for the most part. Green apple aphid populations continue to build and are very high in a few blocks; however most are being controlled quite nicely by predators. Woolly apple aphids are moving out to the terminals of branches and suckers over the last week. European red mite populations are generally under control at many farms, however their numbers are continuing to slowly build. Many blocks have between two and three adult mites per leaf at this time. Two spotted spider mites continue to feed more heavily in apples.
Apple scab continues to show up in higher amounts. With the dry weather over the last two weeks, I suspect that we are at the end of apple scab spore discharge. However, I will know for sure later this morning as we have finally received our first rain event at both apple scab spore monitoring stations. More fireblight strikes are showing up in many blocks across the region. Powdery mildew continues to be seen on fruit and foliage.
Pears continue to size fairly well, with most being in the range of 1.375 inches in diameter. Pear psylla adults continue to fly with particularly high numbers on suckers. These suckers need to be removed at this time.
Peaches continue to size well with most being in the range of 1.5 to 1.75 inches for Red Haven. Oriental fruit moth infected shoots continue to be seen in peaches, as do green peach aphids. Leaf drop from bacterial spot infected foliage continues to cause some extensive leaf drop at a few farms. Fruit thinning is about 60 to 70 percent complete at this time.
Sweet cherry
harvest began for many people over the weekend for early varieties and will
kick off in earnest with mainstream varieties mid-to late this week. This early
harvest of sweet cherries is a record for me in my nearly 30 years of
experience with the fruit industry in southeast
Tart Cherries sized a bit more over the last week, with most being in the range of 19 to 23 mm in size. There has been excellent color development over the last week. I expect to see harvest on tart cherries to begin late this week or over the weekend on early maturing sandy sites, with others beginning next week at this time.
Plums have not sized much over the last week, with most being in the range of 21 to 23 mm in size.
Strawberry harvest continues across the region. Growers to the south report that they feel they are over the peak of their production. Where growers have been able to continue to irrigate strawberries, sizes have remained good. Where irrigation was not applied on a regular basis over the last couple of weeks, berry size is dropping off. There has been strong demand for strawberries this year. I’ve seen another farm over the last week where grubs are actively feeding on roots of bearing strawberries. Growers need to do a good job of scouting for potato leafhopper on newly planted berries.
Raspberries are about 10 days away from beginning of harvest for early summer varieties. This fruit is now coloring. There has been some fruit that have aborted or smaller size fruit, and even some early cane collapse. This cane collapse is due to a combination of winter injury and the Easter freeze event. The early berry drop is also caused by the Easter freeze. Fall red raspberries continue to grow new canes, with most being around 30 to 34 inches in height. Potato leafhoppers have been high in several fields of fall red raspberries.
Blueberries continue to size quite well with most being in the range of 12 to 14 mm in size. More of the fruit is turning to a light blue color. There has been one report of blueberry maggot catch, however I’ve not heard any other reports.
Grapes have now finished bloom for Concords. There has been a report of seeing a grape berry moth at a few farms.
Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar
Hand thinning of apples and peaches is underway where needed. Strawberry harvest is moving along quickly due to the hot temperatures. Sweet cherry harvest will begin soon. Irrigation is being done, where it is available, in small fruits and tree fruits. The area has been without significant rainfall for the last two weeks and tree stress is of concern – especially in newly planted trees. The rule of thumb for newly planted trees is 10 gallons of water per tree per week. The rains this morning, Tuuesday, June 19, were variable with some areas getting under a tenth of an inch to other areas getting about just under a half inch.
Fire blight symptoms from the hailstorms that moved through Saturday, June 2 should be present by now in the effected blocks. If the high winds on June 7-8 caused further trauma blight, those symptoms should show up any day now. It was quite windy again on Monday, June 18 and trauma blight would again be a concern in blocks that have active fire blight in them. The winds will only serve to spread the infection more.
A regional biofix for Oriental fruit moth was set for Grand Rapids area on May 10, and 790 DD45 have been accumulated since then indicating that pest is past peak hatch for first generation, but cover sprays still need to be maintained for another 10 days to prevent damage in stone fruits. Be sure to watch PHI’s on sweet cherries as harvest will be early this year and is getting close. Adult trap numbers have been declining over the past two weeks, but should increase again soon with the start of second generation flight. Lures should be changed to get the best trap numbers.
A regional biofix for codling moth was set for May 20. We have accumulated 514 DD50 since May 20 and 547 DD50 since May 15. Egg hatch should be at a peak level and cover sprays for first generation codling moth need to be maintained well over the next two weeks or so and should be of the most concern in blocks with very high numbers. The more you can do to control first generation, the easier it will be to deal with second generation.
European red mites have been more common this year than normal, and we saw some petalfall miticide applications starting to break in some blocks last week. Numbers of mites per leaf range from 1 to over 10, depending on site, but there seem to be less mites this week compared to last for some reason. Five mites per leaf is the threshold for June. Predators are still difficult to find in European red mite populations.
Green apple aphids continue to be found, but numbers haven’t been building with the very hot temperatures over the last week. Predators can be found in aphid colonies.
Growers in the
The weather last week was very hot, windy and dry. These conditions led to the excess soil moisture loss due to accelerated evapotranspiration. Last night, two weather fronts collided bringing some much needed rain. It appears that the precipitation amounts varied widely throughout the area. Unofficial reports indicate that between late last night and early this morning, we had from about an inch to four inches of precipitation. According to our automated weather stations, the highest rainfall amount of 1.92 inches was registered in the Ludington area, followed by Hart where we had 0.64 inch and the Manistee/Bear Lake area with 0.57 inch. This rain has provided much needed relief from the droughty conditions that were beginning to have an impact on the trees and developing fruit.
Apples are about 1.25 inches in diameter.
Pears are from 22-25 mm in diameter.
Tart cherries are coloring. There is some talk of putting the Ethrel applications on later this week.
Sweet cherries are coloring nicely and will be ready for harvest about a week ahead of normal.
Peaches are an inch in diameter (Redhaven).
Plums are about 25mm in diameter.
Our degree-day accumulation is running ahead of last year; 90 DD50 for Manistee/Bear Lake area, 90 DD50 for Ludington and 148DD50 for Hart area.
West
|
Location |
DD42 |
DD45 |
DD50 |
Rainfall last week |
Rainfall since 4/1 |
|
Hart |
1302 |
1088 |
785 |
0.07 |
5.29 |
|
Ludington |
1183 |
980 |
696 |
0.17 |
6.17 |
|
Manistee |
1278 |
1068 |
771 |
0.24 |
5.32 |
Apple scab lesions from previous infections are evident in a few blocks. Overall, it appears the growers have done a good job through the primary. This has been the second wetting event that did not produce any spores thus getting us out of the primary. Orchards that have lesions on the leaves will be subject to secondary infections. Last night’s rain did not provide a long enough wetting event that would lead to an infection.
Fireblight symptoms following the high windstorm are starting to show up in the area. It is not as bad as originally anticipated.
Cherry leaf spot low infection period is in progress at the time of this report. The situation out in the orchards is better than expected given the amount of inoculum present after the last year’s severe infections. Scouts and consultants are reporting seeing some lesions in a few blocks. At this point, the overall situation is not looking bad.
Powdery mildew is present in quite a few blocks in apples, cherries and peaches.
For the second week now, the codling moth numbers have
significantly dropped in commercial blocks. In the abandoned block, after
leveling off, the numbers have started to go up ever so slightly. Lesser
peachtree borer numbers have significantly declined since last week when we had
our highest number of moths per trap. European mites are becoming more evident
but still below the threshold for most blocks. There are a few blocks where the
mites have been at or above the threshold requiring miticide application.
Obliquebanded leafroller numbers have gone up significantly since last week.
According to the degree-day model, we are at the peak flight in Ludington and
Manistee/Bear Lake areas and about the peak egg hatch for
Growing
degree day accumulations at NWMHRS
GDD42 1259
GDD50 759
Growth
stages at NWMHRS (6/18/07—8:00am)
Apples have 28 mm fruit.
Pears:
Sweet cherries: Hedelfingen, Gold and Napoleon have18-19 mm fruit.
Tart cherries: Montmorency and Balaton have14 mm fruit.
Apricots have 36 mm fruit.
Plums 22 mm fruit.
Grapes: Chardonnay are in bloom.
There is not a lot new to report with the weather, except that it has been hot and very dry in the Northwest for another week. However, rain finally fell last night, June 18, and the area’s rainfall totals ranged from 0.4 inch in Benzonia up to 1.36 inches in Eastport. Prior to this last rain, the NWMHRS received less than 1.5 inches of rain in May and so far in June, we have reported less than a half inch of rain. In a nutshell, the conditions here in the north are extremely dry, and we were happy to receive last night’s rain. Our GDD have really moved along this past week, and we are at 1259 base 42 and 759 base 50; these accumulations show that this year is the hottest on record since 1991.
Many of the trees in the region are now showing symptoms of drought stress; we expect last night’s rainfall will relieve some of these drought signs. We have also observed cherries moving along quickly under these warm temperatures, and some of our early test varieties are already edible. Strawberry harvest has been underway for a little less than a week, and these cooler temperatures will help prolong the harvest.
With these warm and dry temperatures, we have not had an apple scab wetting event since the last of May until last night. The June 18 wetting event is still ongoing and will result in an apple scab infection. The model also indicates that although our spores are 100 percent mature, we still have between 5-10 percent of the spores yet to be discharged. Hopefully, with one final rain, we can call an end to primary scab. We have observed powdery mildew in some apple blocks. In apple, we are seeing our insect numbers stay pretty level compared with the last few weeks. Average trap counts are as follows: spotted tentiform leaf miner- 10 per trap, codling moth- five per trap, obliquebanded leaf roller- 20 per trap, and oriental fruit moth- 10 per trap. We are setting the biofix for obliquebanded leafroller on May 28.
Again, with these warm and dry temperatures, we do not have much to report in the way of cherry leaf spot infection. We have not had a wetting event that would result in a cherry leaf spot infection since May 27. We have observed a few cherry leaf spot lesions on a few blocks, mostly on the small bract leaves. Growers should be especially diligent about preventing cherry lead spot this year as so many trees are experiencing drought stress. Lots of powdery mildew is showing up in tart cherry, as this disease loves hot and dry conditions compared with our other pathogenic fungi. Obliquebanded leaf roller numbers are high in our NWMHRS cherry blocks with a trap average of over 28. Lesser peach tree borer numbers average 10 per trap, while American plum borers have dropped to less than one moth per trap. Greater peach tree borers are flying, and we caught a few per trap this week. As mentioned last week, we caught our first cherry fruit fly, and this week we have captured a total of 18 flies in our unsprayed entomology block. We are still seeing some new plum curculio stings in our entomology block at the NWMHRS. Two-spotted spider mites are showing up in cherry, especially as the ground cover is drying up so early in the season.
Jeff Andresen
Agricultural Meteorology
Geography
A cool front moved across
Looking ahead, the outlooks in general suggest a gradual return of warmer and drier than normal weather. In the near term, a weak frontal boundary is forecast to cross the state late Wednesday into Thursday and bring at least a chance for showers. With only limited moisture in advance of the front, however, any precipitation that does develop will likely be widely scattered in nature with most amounts remaining less than 0.25 inch. Best chances for rainfall through Thursday morning will be across northern sections of the state, with most southern sections remaining dry. A second frontal system will approach the state by Friday, bringing another chance for rainfall. Once again, only widely scattered showers and a few thundershowers are expected, with many areas remaining dry. Warmer and drier weather is a good bet by Sunday continuing into the early part of next week. Temperatures during the next couple of days will remain at near to slightly below normal levels, gradually warming to above normal readings by the weekend. Look for highs ranging from the low 70's north to the upper 70's south through Thursday, increasing into the 80's by Sunday. High temperatures near 90EF are possible once again by Monday of next week. Low temperatures will range from the upper 40's north to low 50's south through Thursday, increasing into the 60's by the weekend.
Medium range forecast guidance is suggesting the formation
of an upper air ridge across the Great Plains and western