In this issue
Tree fruit news
§ Starane Ultra labeled for pome fruits
Small fruit news
§ Botrytis gray mold control in fall raspberries
§ JMS Stylet Oil can be used to knock down powdery mildew on grapevines
Other news
§ Time to collect leaf samples for nutrient analysis
§
§ Regional reports
§ Weather news
Next issue August 19
Bernard Zandstra, Horticulture
Pome fruits (apples and pears) have been added to the
Starane Ultra (fluroxypyr) Section 3 label for postemergence control and
suppression of several broadleaf weeds. This use is labeled in all states
except
Starane Ultra gives good control of many broadleaf weeds,
including common chickweed, ragweed, horseweed (marestail), dandelion, stinging
nettle,
Starane Ultra may be applied at a rate of 0.4 - 1.4 pt/acre (0.125 – 0.44 lb ai/acre) in pome fruits. See the label for weeds controlled at the various rates. Only one application may be made per year. There is a 14 day preharvest interval.
Starane Ultra should not be applied to trees less than four years old. It should not be applied during bloom. Avoid contact with tree leaves as much as possible. Minor phytotoxicity on the trees will not cause permanent injury.
Starane Ultra should help control many difficult mid-season weeds in apples and pears, including dandelion, horseweed and goldenrod. For best effect, it should be applied during the season when weeds are small and growing rapidly.
Labels should be available from dealers.
Annemiek Schilder
Plant Pathology
Gray mold, caused by the fungus Botrytis cinerea, is one of the most important diseases affecting fall raspberries. Fall raspberries are usually at greater risk of infection than summer raspberries because of the prevailing weather conditions, such as lower temperatures, heavy dews and frequent precipitation. Cool, wet weather and heavy rains in the late summer and fall that keep the plants wet for extended periods are conducive to development of the fungus and infection of the fruit. The rainy weather this summer has already resulted in increased Botrytis gray mold pressure in raspberries.
Typical symptoms include a brown discoloration of the fruit and the presence of a gray fuzzy mold, which can rapidly develop and spread to neighboring healthy berries. Symptoms tend to be more severe inside the canopy and on clusters that are closer to the ground. Even if berries look perfectly healthy at harvest, they can change to a moldy mass within 24 to 48 hours.
Botrytis cinerea is a ubiquitous fungus, which is able to grow and sporulate profusely on dead organic matter. It overwinters in old infected canes and plant debris. The spores are airborne and can travel long distances on the wind. When the spores land on plant surfaces, they germinate and can invade the plant tissues directly or through wounds. Overripe berries and bruised berries are particularly susceptible to infection. Latent flower infections, even though they do occur, are not as important in raspberries as they are in strawberries.
Cultural methods are very important for control of Botrytis gray mold. Choosing a site with good air flow can reduce humidity in the canopy considerably. Low-density plantings, narrow rows and trellising can also reduce a buildup of humidity. Good weed control and moderate fertilizer use to avoid lush growth are also important. Selecting a resistant cultivar or, at the minimum, avoiding highly susceptible cultivars will help to reduce the need for control measures. During picking, avoid handling infected berries, since spores can be transferred on hands to healthy berries. Timely harvesting and rapid post-harvest cooling can also help to reduce losses to Botrytis gray mold.
Several fungicides are labeled for control of Botrytis in raspberries. Fungicide sprays during bloom are important to prevent pre-harvest infections, while post-harvest infections can be reduced by sprays close to harvest (e.g., the day before harvest). Switch (cyprodinil + fludioxonil) is a reduced-risk fungicide with excellent systemic and protectant activity against gray mold. It has a zero-day pre-harvest interval (PHI). Another good option is Elevate (fenhexamid), which is a reduced-risk, locally systemic fungicide with a zero-day PHI. Since these fungicides are in different chemical classes, they can be alternated for fungicide resistance management. My recommendation is to save Switch and Elevate for critical sprays, e.g., during wet periods and for sprays closer to harvest. Other fungicides that may be used in the spray program are Captevate (captan + fenhexamid) (three-day PHI), Pristine (pyraclostrobin + boscalid) (zero-day PHI), Captan (captan) (three-day PHI), Rovral (iprodione) (zero-day PHI) and Nova (myclobutanil) (zero-day PHI). To improve the efficacy of Rovral, an adjuvant should be added. Pristine and Nova also provide excellent control of late leaf rust, which sometimes infects the leaves and fruit of fall raspberries.
Annemiek Schilder
Plant Pathology
Powdery mildew is now showing up on grape leaves and clusters. This disease is caused by the fungus Uncinula necator. The powdery mildew fungus can infect all green tissues, resulting in a whitish gray, dusty or powdery appearance. Powdery mildew colonies are mostly present on the upper leaf surface. Infections of young, expanding leaves can result in distortion or stunting. Early berry infections can result in splitting of berries, secondary rots, and undesirable flavors in wine. Late infections are largely invisible except for a web-like necrotic pattern on the berry surface, which can still predispose the berries to rots. Severe infections reduce vine growth, yield, fruit quality, and winter-hardiness. In late summer, the fungus produces small golden-brown to black fruiting bodies (cleistothecia) on infected plant parts. The cleistothecia overwinter in bark crevices of the vine and release wind-disseminated ascospores in the spring. Leaves in proximity of the bark tend to get infected first. Powdery mildew is favored by high humidity and moderately high temperatures (68°F - 81°F). Temperatures above 95°F inhibit new infections.
Most fungicides used against powdery mildew function to prevent new infections. However, since the body of the fungus is fairly superficial in contrast to most other fungal diseases, it is possible to apply contact fungicides to knock down existing infections. In various trials, JMS Stylet Oil (paraffinic oil) has shown to do a very good job in eradicating existing powdery mildew colonies on leaves and fruit. It apparently works by suffocating the fungal mycelium. This product will also kill spores to prevent new infections and has about a week of residual activity. JMS Stylet Oil is sold as both a conventional and an organic formulation and is labeled for use against powdery mildew, Botrytis, mealybugs, mites, leafhoppers, and whiteflies. The label rate is one to two gallons per 100 gal of water, sprayed with ground equipment every 10 to 14 days. Optimum coverage is very important to get good control since the fungicide has to actually contact the fungus colonies to be effective.
It is important to be aware that JMS Stylet Oil can burn plant tissue if used incorrectly. Be sure to read the label very well before use. Add the oil to tank mix formulations as the last ingredient. Read labels of tank-mix partners to be sure they are compatible with oil. Observe all limitations, precautions, and rate recommendations, in particular with acephate (Orthene), copper ammonium carbonate (CCN), copper hydroxide (Kocide), fenvalerate (Asana XL), Mancozeb, Maneb, methamidophos (Monitor), metalaxyl (Ridomil), and triadimefon (Bayleton). Do not tank-mix JMS Stylet Oil with spreader stickers, Nu-Film, or highly ionized nutrient spray materials (e.g., Nutri-Leaf, Bayfolan). These materials can be sprayed separately from oil. JMS Stylet Oil is compatible with urea (up to five lb per 100 gal) and Epsom salt (three lb per 100 gal). Do not use the following chemicals: captan, Folpet, Morestan, organic tin compounds during, with or following an oil spray. Do not use propargite (Omite) with an oil spray or within 30 days of an oil application. Do not use chlorothalonil (Bravo) or dimethoate (Cygon) in a spray program with JMS Stylet Oil. Do not use the following chemicals with JMS Stylet Oil until at least two weeks have elapsed between use of the oil and the chemicals Dyrene, Bravo, Botran, Kelthane, Dikar, Karathane, Ambush, and Pounce. On grapes, do not use copper and oil together when fruit is present and do not apply sulfur within 10 days of an oil application.
In addition, do not spray at temperatures above 90°F (85°F is a good cut-off). It is okay, however, to spray early in the day when it is cooler, as long as the spray has dried when temperatures rise. Do not spray plants that are under heat or moisture stress. Also, do not spray wet foliage and do not spray when freezing temperatures are anticipated within 48 hours of an oil application. Oil will temporarily remove the bloom on grapes, so it should not be sprayed on table grapes within two weeks of harvest. Since JMS Stylet Oil can delay sugar accumulation in the fruit, do not use more than twice during fruit ripening.
Eric Hanson
Horticulture
Leaf analysis is the best way to monitor the nutrition of fruit plantings. This procedure provides a direct measure of the nutritional health of plants as soil tests only provide an estimate. Leaf analyses can be used to diagnose nutritional problems and to identify developing problems before growth or yield is affected. Sample young plantings every one to two years and established plantings every two to four years. The whole farm can be sampled every three to five years, or portions sampled more frequently.
1) Define sampling units. Divide the farm into sampling units or areas that have uniform soil types, management history and variety. Farms with variable soils or history will require more sampling units to provide an accurate picture of the nutritional health. If the farm is very uniform with large blocks of the same age and varieties, define units no larger than 10 to 15 acres.
2) Sampling. Sample leaves in late July to early August. Collect at least 50 leaves from different plants throughout the sampling unit. Select healthy leaves from the middle of this year’s shoots. If the leaves are dusty, rinse them briefly in tap water, and lay them out on a table top until they are dry to the touch.
3) Submitting samples. Package leaves in clearly labeled paper bags, and send them to a reputable laboratory.
4) Diagnosing nutritional problems. If you wish to diagnose a suspected nutritional problem, collect one sample from plants beginning to develop symptoms of the problem, and a second from nearby healthy plants. These samples can be collected at anytime during the season.
MSU Soil and Plant Nutrient Lab, A84 PSSB, MSU,
A & L Great Lakes Laboratories,
Brookside Labs in New Knoxville, OH (419-753-2448, www.blinc.com).
The Northwest Michigan Horticultural Research Station Open
House will be held Thursday, August 21 in
Featured speakers during the event will be Dr. George Sundin presenting information about diseases; Dr. Paolo Sabbatini and Dr. Tom Zabadal discussing a new wine grape variety trial planted at the Northwest Station; and Dr. Diane Alston, a visiting researcher from Utah State University, providing preliminary results in her cherry entomological research here in Michigan.
A Michigan Agriculture Environmental Assurance Program
educational session will also be held in the research station conference room
starting at noon. The session will begin with a free salmon/trout boiled lunch
courtesy of
The Northwest Station Open House is hosted by the Michigan Agricultural Experiment Station, Michigan State University Extension, the Leelanau Horticultural Society, the Northwest Michigan Horticultural Research Foundation and Parallel 45. The education sessions are free and open to all who would like to attend. Tickets for the wine tasting and dinner are available by calling the Leelanau County Extension office at 231-256-9888.
Weather the past two weeks has been seasonal with highs in
the mid-80s and low near 60s, with no significant rainfall. Soils are beginning
to dry. Annual plants such as weeds and field crops are wilting due to water
stress. Storms moved through the region Monday morning (August 4) and left some
much needed rain. Rainfall amounts were between a third and a half-inch, about
enough water for two days. This wetting period (three hours) was not long
enough to be an infection period for many diseases. The forecast for the
upcoming weeks is for cooler and dryer than normal conditions indicating that
the lack of water will continue.
The growing degrees below have been corrected for some missing temperature data
at sites marked with an asterisk*.
|
|
Grapes, April 1 |
|||
|
Location |
GDD 42 |
GDD 45 |
GDD 50 |
GDD 50 |
|
SWMREC: * |
2516 |
2165 |
1635 |
1641 |
|
2583 |
2238 |
1705 |
1700 |
|
|
2331 |
2000 |
1496 |
1492 |
|
The window for leaf sampling for nutrient analysis in southern
Peach fruit are 2.5 to 3 inches in diameter. Harvest of ‘Red Haven,’ PF 14 New Jersey, PF 15A and ‘Starfire’ underway. There are a fair amount of split pits in some varieties. Brown rot symptoms are becoming easier to find and are often associated with split pits. Short rains such as Mondays morning’s storm are enough to cause brown rot fruit infections. X-disease symptoms are easy to find in the area. Bacterial spot symptoms on peach leaves and fruit are fairly widespread. Check the PHI (days to harvest) when applying sprays to reduce bacterial spot. Stinkbug puncture wounds to fruit are more obvious. Watch for western flower thrip damage to peach and nectarine fruit with hot dry weather. Delegate offers a new option for thrip control. Oriental fruit moth trap catches for the second generation are declining.
In cherries, yellowing leaves and leaf drop due to cherry leaf spot and bacterial canker are common. Several orchards have lost most of their leaves. Be sure to check the leaves for signs and symptoms of these two diseases, as the controls are different. The most recent significant cherry leaf spot infection periods in the southwest region were July 2, 13 and 16. No significant infection periods have occurred since.
Apples are 2.5 to
3.0 inches in diameter. Fire
blight infections are still moving and growers report oozing from active
infections. The oozing should stop as the dry weather halts growth. Very few sooty blotch
and flyspeck symptoms have been found. Trap catch for codling moth is up,
indicating the beginning of the second-generation flight. There was no gap
between generations in some orchards. Codling moth entries are easy to see,
especially on yellow skinned varieties. Few codling moth larvae
can be found in the fruit. Small numbers of apple maggots have
been caught for several weeks in southwest
Pears are about 2.5 inches in diameter. Pear psylla numbers are generally low. Sooty blotch and flyspeck are a concern; fungicides should be included in cover sprays. Both codling moth and oriental fruit moth can damage pear fruit at this time.
Blueberry harvest
of the mid-season varieties ‘Bluecrop’ and ‘
Grapes are at or
nearing veraison and early varieties have begun to change color. Grape berry moth trap
catches are up indicating the start of the second generation. Larval stings and
split berries are easy to find in vineyards with light crop and minimum sprays.
Grape leafhoppers
are scarce. Wine grapes need to be protected from potato leafhoppers. Japanese
beetles are easy to find but not abundant. We expect more beetles to emerge
following Monday’s rain. Fungicides at this time should target downy mildew and phomopsis.
Strawberry regrowth is underway. Some growers report poor growth. This seems be due to drought stress, black root rot or insect feeding. Growers should protect against potato leafhoppers to prevent hopper burn and stunting of new growth. Irrigation is very important to get good growth during this dry season.
Raspberry and blackberry harvest is continuing. Growers should be prepared to protect against Japanese beetles.
Cranberries have small green fruit.
The final Monday Fruit Update
meeting will be on Monday, August 18 at the Fruit Acres Farm in
Seasonal weather has persisted for the last two weeks over the southeast region. Precipitation has been hard to come by over the last three weeks at most fruit farms, and many farms are now in need of moisture to replenish dry soils. I think that the fact that we have had a good number of windy days has helped to dry out our soils more quickly than normal. Most fruit farms are irrigating both tree fruits and small fruits at this time, most notably newly planted strawberries, raspberries and apples. Peaches need irrigation as they are nearing maturity. Our season still remains about normal in terms of degree day totals, and may be running a day or two ahead of normal when I look at the beginning of harvest of some of our fruit crops. ‘Jerseymac’ apples and some of the earlier peach varieties have been harvested.
|
Location |
GDD42 |
GDD45 |
GDD50 |
|
Commerce ( |
2473 |
2135 |
1617 |
|
Emmett (St Clair) |
2423 |
2098 |
1588 |
|
|
2464 |
2129 |
1616 |
|
Lapeer (Lapeer) |
2447 |
2116 |
1610 |
|
|
2556 |
2210 |
1685 |
|
Romeo ( |
2529 |
2189 |
1666 |
Apples continue to size well with many being in a range of 2.25 inches to 2.75 inches. Growers have just started to harvest a few ‘Jerseymac’s’ and other summer apple varieties. It appears that ‘Paulared’ harvest is a little over two weeks away from beginning. Generally, ‘Jerseymacs’ and ‘Paulareds’ are sizing very well and coloring nicely. Summer pruning is now in full swing for apples across the region. Now is the time to take leaf samples for tissue analysis for the year in apples and other tree and small fruits. Deer browsing is more prevalent this season than it has been in the last five years or so. Retain applications will begin in the next few weeks on ‘McIntosh’ and ‘Gala.’
Apple maggot emerged about five weeks ago and started with unusually high trap catch numbers on yellow sticky boards. Since then, much lower numbers have been trapped, and it seems the numbers are going down instead of up. This is a bit unusual as generally apple maggot catch and threat can continue all the way through mid-August or so. Thus far this year I have only had a few reports of apple maggot being caught on red ball traps and none in the last two weeks. Remember that apple maggot typically are caught on yellow sticky boards first and give us an indication they are flying. Once they are caught on red sticky ball traps, cover sprays need to be made within five to seven days of their catch to control them.
Woolly apple aphid populations have grown over the last week with several blocks seeing very high numbers of small colonies feeding in the leaf axils on younger wood. Thorough scouting needs to be done at this time to watch for these populations. Japanese beetle numbers have dropped over the last week. I am not certain if this is a result of dry soils or because it is that time of year that we begin to see fewer of them. Let’s wait to see what another week of scouting does in terms of their numbers.
Codling moth trap catches are on the rise for the start of second generation adult flight. Most growers have not biofixed, but I expect to see higher trap catch numbers as we move throughout this next week. Oriental fruit moth trap catches are on the decline now as we are at the end of second generation adult flight. Potato leafhopper populations remain high in a few varieties of apples, but for the most part they are under control. Green apple aphid populations have dropped back to a point where they are under control in all blocks as well. Fall webworm larvae have been seen in fairly low numbers. European red mites are above threshold levels in hotspots in many apple blocks across the region. These hotspots are now starting to expand to encompass more of the entire block. Thorough scouting needs to be done at this time to assess European red mite populations. Two-spotted spider mite adults and eggs are more numerous this week than last; however their numbers still remain below threshold. Apple rust mites continue to be seen, however numbers are fairly low.
Black rot leaf symptoms are more common in apple blocks across the region, and as of yesterday, I started to see fruit rot symptoms in a few apple blocks, especially where mummy’s are present. Powdery mildew is common in many blocks across the region. I am not seeing any sooty blotch or fly speck symptoms, however I encourage growers to continue to monitor and take appropriate control measures through mid-August or so. A small amount of apple sheet scab continues to be seen in a few more apple blocks.
Pears are at two inches in diameter. Pear psylla continues to feed in many pear blocks with all life stages being present. Suckers need to be removed from the inside of trees at this time to help reduce pear psylla populations for this season and next year. Some fabraea leaf spot continues to be seen in a few blocks of pears. Generally, pear blocks have poor finish this year due to cold temperatures in the spring.
Peaches have
taken on a nice swell of growth over the last week, with most being in the
range of two inches to two and seven-eighths inches in diameter. There is quite
a spread of peach sizes as we approach beginning of ‘Red Haven’ harvest, which
is expected to begin in the next four or five days.
Sweet and tart cherry leaf drop has been heavy over the last week or so at many farms. I think this is due to a combination of bacterial spot and cherry leaf spot infected foliage. Even though applications of fungicide have been made in most blocks, this early leaf drop was caused from infections that occurred much earlier in the season. I am a bit concerned about this early leaf drop, as some tart cherries are close to being 60 percent defoliated, with other foliage looking as if it is going to drop early as well. Trees that are defoliated this early in the season are generally much less winter-hardy. Cherry fruit fly populations have declined over the last two weeks. Japanese beetle feeding continues to seen in sweet cherries, again scouting needs to be done. A post harvest application of an insecticide may be needed to reduce both of these pests for this year and future years.
Plums continue to size fairly slowly with most being around 1.25 inches. ‘Shiro’ harvest will begin in the next few days. There are fairly good populations of Japanese beetles still in many blocks of plums. Brown rot is a new pest problem to report over the last week. Black knot continues to be seen in some susceptible varieties as well. I am continuing to see a fair amount of fruit drop in plums over the last four to six weeks. Of late, fruit will begin to color early, and then drop prematurely. I think most of this issue is related to frost and freeze injury and pollination issues. Some of this fruit is also infected with plum curculio larvae.
Strawberries continue to rebound well from the renovation process where soil moisture has been adequate. However, where soil moisture has been short, strawberries have been slow to rebound. This is a concern to me at this time, and I have recommended to several growers that irrigation needs to be applied to push those fields along. Newly planted strawberries are continuing to runner with several filling out the rows at this time. If leaf growth continues as it has on daughter plants, the rows will be filled in fairly quickly. Potato leafhopper feeding is common in many newly planted strawberry fields, and needs to be scouted for thoroughly. White grub feeding injury and plant collapse started to be seen a few weeks ago in newly planted strawberries.
Raspberry harvest for summer red and black raspberry varieties has wrapped up across the region at most farms. Cane collapse has been common due to disease and winter injury as well as dry soils. Fall raspberries have small green fruit present, and most growers are doing a small amount of picking off of lower growing canes. Raspberry cane borer continues to be seen in a few blocks of fall red raspberries; however their populations are pretty well under control. Japanese beetles were feeding heavily in many blocks of fall red raspberries a few weeks ago, however their populations seem like they have dropped back a bit.
Blueberry harvest
continues across the region. ‘
Phil Schwallier
Amy Irish Brown
Carlos Garcia-Salazar
Degree day totals are at normal, average accumulations for this time of the year. With the dryer weather over the last two weeks, tree growth is really slowing down and terminal bud set is commonly found. Many apples have reached the two-inch mark and even larger where crop load is light. Summer pruning is being done in apples.
Retain applications need to be made 30 days ahead of anticipated harvest dates to be the most effective. That means that Retain should go on ‘Galas’ around August 11 and on ‘McIntosh’ around August 14. Even though ‘Honeycrisp’ has a long harvest window, it can still benefit from Retain applications, especially in U-pick situations. Retain should go on ‘Honeycrisp’ around August 18.
Japanese beetles continue to be found, but seem to be
decreasing a bit. I would expect they could still be a problem for another two
weeks at least. Cover sprays are still recommended where Japanese beetles are present.
Our degree day accumulations since the regional biofix for codling moth on May 24 is 1214 DD50 – this indicates that second generation egg hatch is most likely just beginning. Your own trap counts are your best indication of what’s going on in your blocks. On a regional level, second generation codling moth egg hatch is beginning, and cover sprays are once again important to maintain where you have trap numbers over the threshold of five moths per trap accumulated over time for this generation in non-disrupted blocks and two moths per trap accumulated for disrupted blocks.
We’ve accumulated 1682 DD45 at the Sparta station from the May 8 regional biofix for Oriental fruit moth. This indicates that egg hatch for the second generation of Oriental fruit moth should be well underway and we’re probably just past a peak hatch level right now. Cover sprays in peaches and plums are once again crucial to prevent feeding damage to fruits and shoots. Be sure you double-check the PHI of the materials you are using.
Apple maggot adults continue to be trapped in this area
mostly on yellow boards, but also a few here and there on red ball traps. If
you start catching apple maggot flies on red balls, cover sprays are needed
within five to seven days of the catch. I know growers don’t need another
problem to deal with this year, but we don’t want apple maggot to catch anyone
off guard. We haven’t had to deal with much pressure from apple maggot in
recent years in the
All stages of European red mites continue to be found, but they don’t seem to be getting out of hand this year. This is most likely due to all the heavy rains in July. It’s been fairly dry now for a few weeks, so mites are starting to build, but numbers are still well below thresholds for August in most blocks. Unless you are seeing more than seven or eight mites per leaf, you are probably okay to not treat. If you reach that threshold closer to August 15 or so, there should be no need for miticides regardless of the population. Also, with the reduced crop, that threshold is probably on the low side for this season and trees can tolerate a higher level of mites per leaf than in a normal crop set. Predators can be found in many blocks feeding on red mites, so be sure you take them into account as well.
Summer disease symptoms can be seen in unsprayed trees. A second application of summer disease fungicides is needed in susceptible varieties if not applied already.
The harvest of blueberries is in full swing. We have an abundant blueberry crop with good quality. However, there are some problems related to crop management that are causing some concerns at harvest time.
So far, deficient fruitworm control and the presence of mummyberry at harvest are major concerns. Deficient fruitworm control is a major problem, especially in those fields where cherry fruitworm and cranberry fruitworm are occurring simultaneously. This is a problem particularly for small producers with limited resources that are unable to conduct a timely pest control program. There are some reports from packers and shippers indicating that some growers are bringing berries for processing with up to 30 percent fruitworm infestation. Those loads are rejected immediately, or in the best case they are paid less than 30 cents/lb because that fruit will require a good amount of work to be cleaned and processed.
Another situation very similar to this is the presence of fruit with mummyberry. Again, this problem is more prevalent in small operations. Reports from packers and shippers receiving fruit for fresh pack or processing signaled that, in some cases, small producers are bringing fruit with up to 70 percent mummyberry infestation. These loads are immediately rejected.
One explanation for these problems could be that weather conditions that took place during spring time, with abundant rains and cold weather, which allowed for a long bloom period that required a longer insect and disease management program than the one required in a normal year.
Because of the large crop, prices for blueberries are lower
than the previous years. So far, hand-harvested blueberries are sold for $1.00
to $1.25 per pound. But there are some instances in which the prices have been
lower than $1.00 per pound. On the other hand, prices for blueberries destined
for processing are at their lowest. For this reason, growers are trying to
hand-harvest the most they can and machine harvest the least amount of their
crop. So far, prices of blueberries in terminal markets of
The weather has been seasonably warm with temperatures in the 80s for highs and
50s - 60s for lows. With the
exception of the last few of days, high humidity has not been a major problem.
During the last two-week period precipitation has been scarce.
|
Location |
DD42 |
DD45 |
DD50 |
Rainfall July 21-August 3 |
Rainfall since April 1 |
|
Hart |
2191 |
1871 |
1383 |
0.03 |
15.66 |
|
Ludington |
2075 |
1760 |
1280 |
0.05 |
16.46 |
|
Manistee |
2145 |
1829 |
1351 |
1.08 |
16.54 |
Tart cherry
harvest is nearing an end. At the end of the third week of harvest ending
Saturday, July 26, the west-central area delivered a total of 37.8 million pounds.
In the fourth week of harvest, some estimated that
Brown rot is flaring up particularly in stone fruit nearing harvest (apricots, plums, apriums and peaches). Cherry leaf spot symptoms from the storms in June are now very visible in quite a few blocks though overall the picture is fair. In a few blocks there is a possible SI resistance problem. Fireblight is still showing signs of activity. Secondary apple scab lesions could be found sporadically on the leaves and on the fruit. Powdery mildew is widely spread in all fruits.
Codling moth trap catches have been dropping steadily over the last two weeks. Regional biofix for the second generation for the most blocks could fall between July 19 and July 26. The regional biofix was set for July 22 when we had 1059 DD50. Timing for the second-generation control is from 100-250 DD50 depending on the material used. Daily degree-day accumulation has been rapid during these last two weeks. The codling moth degree-day model indicates that the egg hatching of the second-generation has begun.
Oriental fruit moth flagging is evident in many peach
blocks. Scouts report finding larvae in the fruit. American plum borer trap
catches have gone up since last week. Lesser peach tree borer trap catches have
been inconsistent; in the first week of the last two-week period there had been
a noticeable drop whereas in the last week there had been a significant
increase in the trap catches. Greater peach tree borer trap catches have been
dropping slowly in the first week with more significant decline in the last
week. Cherry fruit fly numbers are up. Apple maggot is out. Scouts have
reported catching apple maggot in
Now is the time to collect and submit leaves for foliar analysis.
Nikki Rothwell
Duke Elsner, Erin
Lizotte, Rob Sirrine
GDD42 2214
GDD50 1406
The weather has been warm and dry for the past few weeks, which has been good for harvesting cherries. Not much rain has fallen in the last week, and overall rainfall for July was 2.27 inches. The total rainfall for 2008 is 7.21 inches. The forecast is calling for isolated thundershowers today. Total degree day accumulations as of the morning of August 5 are 2214 base 42 and 1406 base 50, which are only slightly behind our 18 year average.
Sweet cherry harvest has finished in the region, and quality was a challenge with lots of brown rot and alternaria. Tart cherry harvest is still underway, and again quality has been less than optimal. Wind whip, and its related issues, is the primary cause of downgrades at the processor. Fruit is large in size, and processor reports have mentioned that fruit is so big that it has been difficult to pit. Harvest is expected to continue through this week. Balaton® fruit set is light, and harvest is beginning in southern orchards of the northwest region. Red raspberry harvest has finished, and plums are starting to ripen. Later varieties of apricots were harvested at the station last week.
Obliquebanded leafroller numbers are down with an average of seven per trap in the station trap line. Lesser peach tree borer and American plum borer numbers remain low, with less than 10 per trap for the third week in a row. Greater peach tree borer emergence is averaging 20 per trap for the second week. Cherry fruit fly numbers continue to be a concern. Last week, we caught 86 flies, this week the traps are averaging in the teens. Powdery mildew is quite prevalent on new growth in tart cherry orchards. American brown rot has been widespread and severe this year with many growers choosing to partially or completely abandon some sweet cherry blocks. Brown rot and alternaria has been observed in tart cherries. We have been observing high levels of cherry leaf spot around the region. Post-harvest chlorothalonil applications will be critical in helping to reduce early defoliation this year and inoculum levels next year.
Spotted tentiform leafminer trap catches are down from last week’s high trap catch of 186, averaging 26 per trap this week. We caught just one obliquebanded leafroller. Oriental fruit moth catches are rising at the station, but remain relatively low at three to 15 per trap. We have accumulated 1105 DD50 since first generation codling moth emergence, so we are expecting second generation flight any time now. One area scout reported an apple maggot a few weeks ago, but we still have not caught any at the station nor received any other reports of apple maggot from growers. European red mites and two-spotted spider mites have reached threshold levels in some area orchards.
Little has changed in grapes over the past weeks. We are starting to see powdery mildew in clusters and on foliage. Isolated phomopsis infections have also been observed. Downy mildew has been seen in area vineyards, and we are starting to see grape berry moth webbing. Potato leafhopper populations are still at low levels. Lastly, sunscald has been seen where hedging has occurred prior to the intense sun we have seen over the past week. Symptoms of sunscald include brown spots isolated on berries where they are exposed to the sun.
Jeff Andresen
Agricultural Meteorology
Geography
During the past one to two weeks, a broad upper air ridge
has persisted across much of the central United States, resulting in oppressive
heat across sections of the southern and central Great Plains and generally
drier than normal conditions across much of the Upper Great Lakes region. That
pattern is expected to continue for much of the next one to two weeks, but with
a shift of the ridge axis westward into the
In the short term, cooling temperatures aloft and a series of weak upper air disturbances will lead to the chance for scattered showers and a few thundershowers Wednesday, August 6, through Friday. Given limited low level moisture, however, rainfall amounts and areal coverage are expected to be limited with most totals remaining in the 0.10-0.25-inch range or less where rain falls. Fair, dry and cool weather is expected for the upcoming weekend. Temperatures Wednesday through Saturday will fall back from recent levels to highs ranging from near 70°F north to 80°F south, with lows from the low or mid-50s north to near 60°F south. A weather system approaching from the west will bring the next chance for significant rainfall by next Monday or Tuesday.
In the medium range period, forecast guidance suggests a general continuation of the upper air pattern mentioned above. Both National Weather Service 6 ‑ 10 day, covering August 10 – 14, and 8 ‑ 14 day, covering August 12 – 18, outlooks call for below normal mean temperatures and precipitation totals state- and region-wide. Given good agreement amongst the guidance tools used to create the outlooks, forecaster confidence is considered greater than normal.
Latest long lead forecast guidance suggests that the El Niño
Southern Oscillation (ENSO) index will remain near neutral for the next several
months into early 2009 at least. Thus, while some impacts of the recent past La
Niña event may persist for another month or two (including increased chances
for hurricane activity in the northwestern
The latest NOAA long lead outlook for August calls for mean
temperatures in