June 15, 2005
In this issue
§ Potato leafhopper numbers are increasing
§ Colorado potato beetle larvae expected
§ Growers should be alert for squash vine borer and squash bugs
§ Aster leafhoppers and aster yellows
§ European corn borer trap catches
§ Disease alert for vegetables
§ New products for disease control in carrots
§ Onion disease forecaster updates
§ Postemergence weed control in vegetable crops
§ Crop damage by lightning: Unusual problem with serious losses
§ Mark your calendar: Muck Farm Field Day
§ Regional reports
§ Weather news
Increasing numbers of potato leafhoppers (see photo of adult and nymphs) are being found in potatoes and snap beans. Both of these crops are susceptible to hopperburn damage by potato leafhopper, resulting in leaf cupping and yellowing or browning of leaf tissue (photo). By the time damage is visible, plants have been injured and yield losses are likely. Potatoes should be treated if numbers exceed 0.5 adult leafhoppers per sweep or 1 nymph per 10 leaves. Snap beans require treatment if numbers reach 1 per sweep or 5 per foot of row (2 per foot for seedlings).
Egg laying is well along in some locations and first egg hatch is expected this week. If control is needed, Rimon is most effective on small larvae, SpinTor and Agri-Mek are recommended if mixed populations of adults and larvae are present. A foliar neonicotinoid (Provado, Actara) can be used if a neonicotinoid was not used at planting (Admire, Platinum) or as a seed treatment (Cruiser, Genesis). Using a foliar neonicotinoid after at planting application or seed treatment with a neonicotinoid can lead to serious insecticide resistance problems.
If treatment is needed, Michigan State University Extension bulletin E-312, Insect, disease, and nematode control for commercial vegetables, is available on the web at:
http://web4.msue.msu.edu/veginfo/bulletins/E312/index.htm name="_Hlt103500056">. Bulletin E-312 is also available in hard copy from your local MSU Extension office or from the MSU Bulletin office at: http://web2.msue.msu.edu/bulletins/mainsearch.cfm. Product labels and material safety data sheets are available at http://www.cdms.net/pfa/LUpdateMsg.asp.
Squash vine borer tunnels in vines of summer and winter squash and pumpkins. Adults begin to mate and lay eggs on squash vines in June. Once eggs hatch and larvae enter the vine, control is not effective. Pheromone lures specific for squash vine borer are available from commercial pest management suppliers and can be used in traps to determine adult activity and accurate timing for sprays.
Squash bug adults may move into early squash fields from overwintering sites. Growers and scouts should watch carefully for egg laying and hatch of nymphs. Large nymphs and adults are very difficult to control, so insecticides should be timed to control small nymphs. If you wait too long, it may be a continuous battle for the rest of the summer.
Detailed articles and photos of these insects are available in the University of Illinois IPM Newsletter number 9 (http://www.ipm.uiuc.edu/ifvn/volume11/frveg1109.html - veg).
MSU’s Diagnostic Services have tested aster leafhoppers (see photo)from celery and carrot fields in western Michigan for the presence of aster yellows. At most sites, including sites in Hudsonville, Wayland, Decatur and Allendale, no infected leafhoppers were found. We recommend a conservative estimate of 2 percent infected leafhoppers for these sites, which translates into a treatment threshold of 18 aster leafhoppers per 100 sweeps in celery, 25 per 100 sweeps for susceptible varieties of carrots and 50 per 100 sweeps for resistant carrot varieties. One carrot field in Ravenna and another in Mears had 6 percent infected leafhoppers (8 leafhoppers per 100 sweeps for susceptible carrot varieties). Last week a celery field in Freemont had 1.3 percent infected leafhopper (27 leafhoppers/100 sweeps for celery).
Recent weather patterns may encourage migration of aster leafhoppers from the southern United States into Michigan. Growers are encouraged to scout celery, carrot and lettuce fields for the presence of aster leafhoppers. Aster leafhoppers may be sampled by taking sweep net samples, preferably 25 sweeps in each of eight different areas of the field, for a total of 200 sweeps. Aster leafhoppers should be counted and the total number divided by two to get the number of leafhoppers per 100 sweeps. To determine the treatment threshold, divide the following numbers by the infectivity rate: Celery - 35, Carrots, susceptible varieties - 50, Carrots, resistant varieties - 100, lettuce - 25. For example, at 2 percent infectivity the treatment threshold for celery is 17.5 leafhoppers per 100 sweeps, for lettuce it is 12.5 leafhoppers per 100 sweeps and for susceptible carrots it is 25 per 100 sweeps. At 5 percent infectivity the treatment thresholds are 7 for celery, 10 for susceptible carrots and 5 for lettuce. If the number of leafhoppers caught in a sample exceeds the calculated treatment threshold, then treatment is warranted.
The number of European corn borer moths caught in pheromone traps increased dramatically last week, as the weather finally warmed, and degree-day accumulations (base 50) reached the 450 to 500 required for the first flight of moths.
The numbers jumped throughout Michigan; in Monroe County the trap catch increased to 24 per trap, in Mason County numbers increased from 2 to 8 per trap. On campus the numbers jumped from 1 to 30 per trap. Egg laying can be expected to continue in full force for the next few weeks.
The recent warm, wet and humid weather is favorable for disease development. Hail damage, along with high winds and rain, increases the threat of bacterial disease to susceptible crops such as tomatoes. The physical damage to the plant caused by the hail opens up entry sites for the bacterium. Wind-driven rain moves the bacterium from infected plants to nearby healthy plants. While copper applications should be helpful, I’m concerned about the use of coppers during times of extreme temperatures. Further, if the copper does not dry readily because of the humidity, then phytotoxicity is more likely. Adding an EBDC fungicide, such as Dithane or Mancozeb, to the copper may offer enhanced control of bacterial disease. Tomato growers should also scout their fields for early symptoms of early blight and Septoria. Both of these foliar blights are favored by warm, wet and humid conditions. Preventive fungicides are certainly warranted given the weather we’ve experienced.
Foliar blights on carrots, celery and onions are likely to occur especially early this year given the August-like weather. Growers should be scouting carrot fields carefully in order to time initial sprays. If Cercospora is detected on carrots – even a small amount – sprays should begin immediately. Applications of Bravo or Quadris are recommended. Depending on the disease severity, spray intervals of ten days may be needed for carrots if the TOM-CAST disease forecasting system is not being followed. Onions and celery crops should be treated preventively with fungicides to protect against the foliar blights. If it seems too early to be applying fungicides or if you are hesitant to apply full rates, you may want to reconsider. When diseases occur early in the season, they have the most potential to cause severe damage and crop loss. A well-timed and executed fungicide program will be critical for many vegetable crops this season.
Cercospora and Alternaria blights occur every year in Michigan carrot fields and require management to prevent crop loss. Cercospora blight is caused by the fungus Cercospora carotae and is the most important foliar disease of carrots in Michigan. The fungus can attack young foliage, either on the leaves or petioles, causing blight. Alternaria blight is caused by the fungus Alternaria dauci and is usually detected later in the season on older foliage. Warm temperatures and long periods of leaf wetness promote disease development. Spores of these fungi are wind-blown to nearby plants or even adjacent fields. Methods to reduce disease pressure include planting disease-free seed, following a two-year crop rotation, minimizing overhead irrigation during warm weather, and applying fungicides. Methods to effectively schedule fungicide applications according to field scouting and the Tom-Cast disease forecasting system have been developed.
Fungicides were evaluated at the MSU Muck Soils Research Farm in 2004 (Table 1). ‘Fontana’ carrot seeds were planted at a density of 22.8 seeds/ft of row on June 21 in three seed lines per row with rows centered 16 inches apart on three-row raised beds centered 64 inches apart. Treatment plots consisted of one row 20 ft long with 5 ft of unsprayed buffer between plots in the same row. One bed was left unsprayed between treatment plots. Twelve treatments were replicated four times in a randomized complete block design. Fungicides were applied with a CO2 backpack sprayer equipped with three XR8003 flat fan nozzles spaced 18 inches apart and calibrated to deliver 50 gal/A at a nozzle pressure of 52 psi. Ten weekly applications were made on August 6, 13, 20 and 27; September 3, 10, 17, and 24; and October 1 and 5, except for the 14-day treatment of Bravo Weather Stik 6SC which received five applications on alternate dates. The combined effect of Cercospora and Alternaria blight was assessed from plants in the center 10 ft of the middle row of each plot on October 11. Carrots in the center 10 ft of the middle row were hand-harvested, the foliage was removed with a mechanical topper and root yields were recorded on October 11.
|
Product |
Active ingredient(s) |
Manufacturer |
Registered |
|
Amistar 80WG |
azoxystrobin |
Syngenta |
Yes |
|
Bravo Weather Stik 6SC |
chlorothalonil |
Syngenta |
Yes |
|
Cabrio 20WG |
pyraclostrobin |
BASF |
Yes |
|
Endorse 2.5WP |
polyoxin D zinc salt |
Arvesta |
No |
|
Kocide 2000 53.8DF |
copper hydroxide |
Griffin |
Yes |
|
Pristine 38WG |
boscalid + pyraclostrobin |
BASF |
No |
|
Switch 62.5WG |
cyprodinil + fludioxonil |
Syngenta |
Yes |
Cercospora blight was the primary disease in this trial and
was detected during the first week of August. Few Alternaria blight symptoms
developed on mature foliage in late September. Leaving plots untreated resulted
in severe petiole (greater than 50 lesions/plant) and leaf (68%) blight (Table
2). When compared to the incidence of petiole blight of untreated plots, applications
of Cabrio 20WG (8 and 12 oz/A), Amistar 80WG (3 and 5 oz/A) or Pristine 38WG
reduced petiole disease when applied in alternation with Bravo Weather Stik 6SC
or when Bravo Weather Stick 6SC was applied weekly (1.5 and 1 pt/A). All
fungicide programs, except Switch 62.5WG, reduced the severity of petiole
blight and improved petiole health compared to the untreated. No significant
improvement in disease control or yield occurred when higher rates of Cabrio
20WG or Amistar 80WG were used. Applications of Switch 62.5WG did not differ
from the untreated control for all parameters measured. Cabrio 20WG (8 and 12
oz) alternated with Bravo Weather Stik 6SC resulted in significantly higher
yields than the Switch 62.5WG treatment and the untreated. No phytotoxicity was
observed from any treatment.
|
Treatment
and rate/A (application sequencez) |
Petiole
blight |
Petiole
healthw |
Leaf
blight (%)v |
Yield
per 10-ft row (lb) |
||||||
|
Incidence
(%)y |
Severityx |
|||||||||
|
Untreated |
97.9 |
eu |
5.0 |
c |
7.5 |
d |
68.2 |
d |
14.7 |
c |
|
Bravo Weather Stik 6SC 1.5 pt (1-10) |
22.0 |
abcd |
1.5 |
ab |
1.8 |
ab |
5.5 |
abc |
24.6 |
ab |
|
Bravo Weather Stik 6SC 1.5 pt (1,3,5,7,9) |
74.6 |
de |
2.5 |
b |
3.3 |
bc |
13.8 |
c |
25.1 |
ab |
|
Bravo Weather Stik 6SC 1 pt (1-10) |
18.4 |
abc |
1.8 |
ab |
2.0 |
abc |
4.2 |
ab |
25.0 |
ab |
|
Cabrio 20WG 8 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
5.3 |
ab |
1.0 |
a |
1.3 |
a |
2.8 |
a |
26.1 |
a |
|
Cabrio 20WG 12 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
2.4 |
a |
1.5 |
ab |
2.0 |
abc |
6.2 |
abc |
27.3 |
a |
|
Amistar 80WG 3 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
9.7 |
abc |
1.0 |
a |
1.8 |
ab |
3.6 |
a |
24.4 |
ab |
|
Amistar 80WG 5 oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
8.0 |
abc |
1.0 |
a |
1.5 |
a |
3.6 |
a |
25.0 |
ab |
|
Endorse 2.5WP 2.2 lb (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
41.5 |
bcde |
1.8 |
ab |
1.8 |
ab |
4.7 |
abc |
23.2 |
ab |
|
Kocide 2000 53.8DF 1.5 lb (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
44.3 |
cde |
2.3 |
ab |
3.5 |
c |
12.5 |
bc |
25.8 |
ab |
|
Pristine 38WG 10.5
oz (1,3,5,7,9) Bravo Weather Stik 6SC 1.5 pt (2,4,6,8,10) |
18.0 |
abc |
1.0 |
a |
2.3 |
abc |
5.1 |
abc |
23.9 |
ab |
|
Switch 62.5WG 11 oz (1-10) |
97.6 |
e |
4.5 |
c |
6.3 |
d |
55.6 |
d |
18.7 |
bc |
z Application sequence: 1 = 6 Aug; 2 = 13 Aug; 3 = 20 Aug; 4 = 27 Aug; 5 = 3 Sep; 6 = 10 Sep; 7 = 17 Sep; 8 = 24 Sep; 9 = 1 Oct; 10 = 5 Oct.
y Percentage of plants from 10 ft of the center row with
at least one petiole lesion.
x Petiole blight severity rated on a 1 to 5 scale; where 1 = 0 petiole lesions per plant, 2 = 1-10, 3 = 11-21, 4 = 21-50, and 5 = > 50.
w Petiole health rated on a 1 to 10 scale; where
1 = healthy and vigorous to 10 = necrotic or dead.
v Evaluated using a leaf blight assessment key
representing the percentage of disease foliage.
u Means within a column followed by the same
letter are not significantly different according to Tukey’s Studentized Range
Test (P=0.05).
A second study was conducted at the MSU Muck Soils Research Farm to examine nozzle types, spray pressure and reduced fungicide rates. A higher spray pressure (100 psi) was used when applying fungicides at reduced rates. Fungicides were applied with a CO2 backpack sprayer equipped with either three XR8002 flat fan nozzles or three 8002 twin-flat fan nozzles spaced 18 inches apart and calibrated to deliver 30 gal/A at 50 or 100 psi. Nine applications were made on August 6, 13, 20, and 31; September 7, 14, 22, and 29; and October 5.
Cercospora incidence was first noted at the beginning
of August and progressed to moderate levels by the end of September. At the
time of harvest, all treatments (regardless of rate, nozzle type and spray
pressure) had significantly better ratings of foliar infection, petiole
severity and plant health than the untreated (Table 3). There was no
significant difference among the treatments for these same ratings and values
were similar. Significant differences among the treatments were noted for
petiole infection. All treatments, except the reduced rates of Bravo Weather
Stik 6SC (0.75 pt) applied every seven days at 100 psi, had significantly fewer
infected petioles than the untreated. Spraying Cabrio 20WG (0.5 lb) in
alternation with Kocide 2000 54DF (1.5 lb) at 100 psi, either with flat or
twin-flat fan nozzles, resulted in the fewest infected petioles. There was no
significant difference in control when using a reduced rate of Bravo Weather
Stik 6SC (0.75 pt) alternated with Cabrio 20WG (0.38 lb) and increasing the
pressure with both nozzle types. Though not significant, there was an increase
of infected petioles (20 to 25.8%) when reducing the rate of Bravo Weather Stik
and increasing pressure for either nozzle type. Plots were hand-harvested,
keeping carrot loss to a minimum, and no significant differences in yield were
noted among the treatments.
|
Treatment and rate/A, applied at 7-day intervals |
Nozzle type |
Spray pressure (psi) |
Foliar infection (%)z |
Petiole |
Plant healthx |
Yield (lb/10 ft) |
|||||
|
Severityy |
Infection (%) |
||||||||||
|
Untreated |
– |
– |
45.0 |
bw |
4.5 |
b |
98.9 |
d |
5.3 |
b |
17.9 |
|
Bravo Weather Stik 6SC 0.75 pt |
Flat fan |
100 |
10.0 |
a |
2.0 |
a |
75.6 |
bcd |
2.0 |
a |
23.5 |
|
Bravo Weather Stik 6SC 1.5 pt |
Flat fan |
50 |
7.5 |
a |
2.0 |
a |
49.8 |
ab |
1.3 |
a |
23.0 |
|
Bravo Weather Stik 6SC 0.75 pt |
Twin fan |
100 |
7.5 |
a |
1.9 |
a |
80.3 |
cd |
1.5 |
a |
23.4 |
|
Bravo Weather Stik 6SC 1.5 pt |
Twin fan |
50 |
7.5 |
a |
1.9 |
a |
60.3 |
abc |
1.8 |
a |
25.4 |
|
Bravo Weather Stik 6SC 0.75 pt alternate
Cabrio 20WG 0.38 lb |
Flat fan |
100 |
5.0 |
a |
1.9 |
a |
41.7 |
ab |
1.0 |
a |
23.0 |
|
Bravo Weather Stik 6SC 1.5 pt alternate
Cabrio 20WG 0.5 lb |
Flat fan |
50 |
5.0 |
a |
1.8 |
a |
40.8 |
a |
1.0 |
a |
26.5 |
|
Bravo Weather Stik 6SC 0.75 pt alternate
Cabrio 20WG 0.38 lb |
Twin fan |
100 |
5.0 |
a |
2.0 |
a |
58.7 |
abc |
1.0 |
a |
26.4 |
|
Bravo Weather Stik 6SC 1.5 pt alternate
Cabrio 20WG 0.5 lb |
Twin fan |
50 |
6.3 |
a |
2.0 |
a |
40.7 |
a |
1.3 |
a |
20.9 |
|
Cabrio 20WG 0.5 lb alternate
Kocide 2000 54DF 1.5 lb |
Flat fan |
100 |
5.0 |
a |
1.9 |
a |
30.7 |
a |
1.3 |
a |
21.1 |
|
Cabrio 20WG 0.5 lb alternate
Kocide 2000 54DF 1.5 lb |
Twin fan |
100 |
5.0 |
a |
1.8 |
a |
31.8 |
a |
1.0 |
a |
23.2 |
z Based
on a visual estimation of the percentage of foliage infected.
y Severity
of petiole infection based on visual estimation utilizing a 1 to 5 scale (1=no
lesions, 5=>50 lesions per petiole).
x Overall
plant health rated on a 1 to 10 scale, where 1=no sign of foliar infection,
10=complete defoliation.
w Column means with a common letter or with no letter
are not significant different, Fisher LSD, P=0.05.
With recent weather conditions favoring disease development, all of the onion disease forecasters have been initiated at the MSU Muck Soils Research Farm located near Laingsburg, Michigan. The Neogen Envirocaster was set up on April 29 and the forecasting models have been collecting and analyzing weather data since early May.
The Onion Leaf Blight predictor has issued moderate to high infection alerts for the last seven days. The Onion Downy Mildew seasonal predictor is running above treatment threshold, and the daily threat indicator has issued high-risk alerts for the last week. The Onion Purple Blotch predictor has issued a high-risk alert for five of the last seven days.
Since all predictors have issued a high-risk alert in the last seven days, growers should consider applying a protectant fungicide in the near future.
With the recent rains in much of the state, weeds have exploded all over. During the extended dry period earlier this summer, there was little weed pressure. However, preemergence herbicides dissipated to a large extent during the hot, dry period, and consequently, the weeds all germinated when the rain came.
Spray postemergence herbicides on crops as soon as weeds are visible. It is much easier to kill weeds in the cotyledon or one leaf stage than when they are larger. Unfortunately, weeds can grow several inches a day in hot, humid weather. In many cases, weeds pass their susceptible stage in a few days, and if growers miss the opportunity to spray postemergence herbicides, their only alternative may be cultivation or hand weeding. If it is too wet to spray and weeds get big, growers may want to increase postemergence herbicide rates to the maximum allowed and add a surfactant if recommended or allowed on the label. Usually, weed pressure will cause more serious crop suppression than slight stunting from a high dose of herbicide.
Many weeds continue to germinate during the summer. Therefore, growers may want to apply another preemergence herbicide to extend preemergence weed control for another four to six weeks. Check labels for preharvest intervals. Most preemergence herbicides do not have postemergence activity but some do. Caparol, Lorox, atrazine, Sandea, Chateau, Spartan, Nortron, Sencor, Sinbar and others are active pre and post at normal use rates. Other herbicides, such as Goal, Reflex and Callisto, have both pre and post activity, but need higher rates than normally used on vegetables to be active pre.
Read labels to determine whether an herbicide will control a certain weed. Spraying an ineffective herbicide wastes money and time and does nothing for the crop.
Please see Extension Bulletin E-433 for current vegetable weed control recommendations. It can be read on line at: www.msue.msu.edu/vegetable/.
There are approximately 100,000 thunderstorms in the United States every year. About 10 percent of these thunderstorms are classified as severe and usually cause significant crop losses. The most obvious losses are those associated with flooding, wind and hail damage. One type of crop loss that is not always visible, at least immediately following the thunderstorm, is damage by lightning.
Our celery experiment at a grower’s farm in Hamilton was hit by lightning last week. Diagnosing the damage would not have been an easy task, had the grower not been familiar with crop damage by lightning. The symptoms on celery looked similar to those of a burndown herbicide or a flamer. However, the pattern of damage is very specific. The pattern was a circle of about 50 to 60 ft diameter (Photo 1). The damage was most severe at the center of the circle and dissipated out to the edges. In the middle of the circle, plants in the inner 10 ft diameter were completely fried (Photo 2). Plants in the outer 40 ft diameter lost a few leaves, were weakened, and are now being attached by plant pathogens (fungi or bacteria) further complicating the diagnosis (Photo 3).
Although this might seem insignificant, an estimated 2,500 to 4,000 celery stalks were lost. If this type of disaster occurs multiple times within the same year (which is possible according to the grower), the losses will add up.
During a thunderstorm, there is a buildup of positive and negative electrical charges that are discharged as lightning (bolt or thunderbolt). Some thunderbolts can reach 15,000 to 60,000oF in a fraction of a second. This rapid change in air temperature (rapid heating and cooling) causes thunder, while the high temperature causes damage to living organisms, including plants.
More information on thunderstorms and lightning can be found
at:
http://www.usatoday.com/weather/resources/askjack/walightn.htm
Michigan State University Muck Farm Field Day at the MSU Muck Research Farm near Bath, Michigan. The field day program will begin with a welcome at 4:00 PM followed by a field tour, catered meal and a second field tour. For additional details, contact Darryl Warncke at (517) 355-0271, ext. 1270.
We had above normal temperatures for the week with highs
ranging from 81o to 91oF and lows 66o to 72oF
at SWMREC. Precipitation in the area ranged from 0.2 to 2.0 inches. Some areas
are still substantially below normal in precipitation with no moisture reserve
in the soil while other areas have standing water in the fields.
Asparagus harvest continues but is quickly winding down. Harvest has already stopped in many fields and weed control is being applied. Harvest will probably to be finished after this weekend.
Vine crop growth has been considerable over the past week. Tunneled plantings are in flower and harvest has begun on tunneled yellow squash and zucchini. Out-of-tunnel cucumber plantings are at tip over. Some wind damage has been seen on summer squash and some plants are collapsing in wet fields.
Early planted, non-tunneled tomatoes are in bloom and many fields are being staked and tied. Warm weather has caused some growers to get behind on staking and tying. Cool conditions should allow them to get caught up.
Peppers are at early flower.
Watermelon and cantaloupe are running off the plastic and are at first flower.
Potatoes are in bloom.
Above normal temperatures and humid conditions persisted during the past week. The area received very little of the rainfall that covered most of the state. Fremont (Newaygo County) had 0.5 inch on Saturday (June 11). Amounts in most of the vegetable production areas were less than 0.1 inch.
Due to the extended dry period, asparagus harvest will essentially be over this week. Quality is terrible and spear diameter is small. Rust is being found in young plantings, asparagus beetles are plentiful and weeds are now growing well in most fields. Preliminary estimates are that the crop will be down at least 25 percent from last year if not more.
Carrot plantings continue to do well with irrigation being applied on many fields. Drier soil conditions at this time will encourage roots to go deep for moisture, which is good.
Planting of vine crops is completed with planting of pumpkins this past week. Emergence has been rapid with the warm soil temperatures, however, it is variable in some fields due to the dry weather. Poor stand in one winter squash field was also affected by birds digging up and eating the seed.
Snap bean fields look good at his time. European corn borer trap counts yesterday (June 14) at Mason County site were 12, 9 and 2.
Spinach harvest continues but has been adversely affected by the hot, dry weather. Bolting has occurred and some of the acreage will not be harvested.
Spotty rains have helped most areas but rains have been 0.6 inches or less. Soil temperatures have finally reached mid to upper 60s with air temperatures in the 70s to 90s. Some areas had hail last weekend.
Potatoes are emerging fast with the soil temperatures and moisture that is available. Colorado potato beetles are laying eggs this week.
Snap beans have been bothered by bean leaf beetle already this year with the first trifoliate just emerging. Sweet corn is catching up as warmer temperatures have helped.
Five days in the 90s this week brought
on tremendous crop growth. Scattered thunderstorms and rain brought variable
amounts of rainfall to the area nearly every day, and I believe there is
sufficient moisture at this time in the region. Keeping up with weeds is a big
challenge and is being accomplished mostly by hand.
Sweet corn and Indian corn are putting on growth
quickly. Where the earliest plantings took a month to emerge, seed planted this
month is emerging within less than a week. European corn borer activity exploded
this past week with up to 67 male moths caught in one trap.
Growth of tomatoes has been
spectacular and some plantings of early varieties are showing some flowers.
In cucurbits, striped cucumber beetles are
present. Squash and melons are responding to warm temperatures. Zucchini
harvest for wholesale is projected to begin in early July while plasticulture
plantings will be ready for harvest sooner.
In cole crops, cabbage flea beetles are in
present in high numbers.
Carrots and onions are looking as good as they ever have and an early harvest of carrots is predicted (Photo 1). High temperatures and prolonged leaf wetness are causing growers to initiate disease treatments on onions this week (Photo 2).
This last week some local farms have received rainfall totaling nearly two inches while others have received less than one quarter of an inch. In some cases these extremes may be less than a mile apart. Night temperatures have remained high and crops have responded with tremendous growth.
Sweet corn has made very good growth again this week with earliest corn still not showing tassels except where planted under tunnels very early. Growers who planted in early April anticipated a very early crop this year and are now realizing that will not happen. Corn borer traps averaged 23 moths per trap this week; however, very little corn is far enough along to be concerned about this first generation.
Tomato planting is complete with early processing tomatoes beginning to blossom. Market tomatoes have fruits up to two inches. No diseases or insects have been seen on this crop.
Peppers are making good growth with the very warm days and nights.
Cabbage harvest is just beginning with larger volume by early next week Diamondback moth traps continuing to capture more than 150 moths per week. No thrips have been seen so far this season. Very few larva of any of the cabbage insects have been seen.
Vine crops are developing very well with the warm weather. Summer squash and zucchini harvest is getting started. Cucumbers are developing fruits, even on bare soil culture. Plastic culture is being harvested now. Cucumber beetles are very thick in untreated fields.
Potatoes planted early are in full bloom. Leafhopper numbers have jumped to 7 per 20 sweeps, still below threshold of 10 per 20 sweeps, but well above previous week’s collections. No Colorado potato beetles in fields.
Snap beans are heavily infested with bean leaf beetles and a few leafhoppers. Controls are being applied in most fields.
Cooler, less humid weather is in store for Michigan the next several days following the passage of a cool front across the state Tuesday (June 14). The frontal passage was associated with the formation of an upper air troughing feature over the Great Lakes Region and is expected to remain through Saturday. Cold, cyclonic flow aloft over the region will lead to the chance for mainly afternoon or early evening showers both Wednesday and Thursday with best areal coverage of precipitation in northern and eastern sections of the state (Only isolated rainfall is expected across southwestern sections of the state.). Precipitation amounts will generally be less than 0.25 inches where rain falls.
Fair and dry weather is expected Friday continuing through the upcoming weekend. High temperatures will range north to south from the upper 50s to mid-70s Wednesday and continue at those levels through Saturday. Low temperatures will range from the low 40s to mid 50s Thursday through Saturday. A significant warming trend will begin on Sunday as an upper air ridge currently over the Great Plains moves eastward into the Midwest. This ridge is expected to become the primary weather story in the medium range time frame with both the 6-10 day (for June 20-24) and the 8-14 day time frame (covering June 22-28) outlooks calling for above normal temperatures and for below normal precipitation. These outlooks are reason for concern in some sections of the state.
Some areas have experienced significant rainfall during the past several days (e.g. the central Lower Peninsula), while other areas have remained mostly dry, especially in far western sections of Lower Michigan. Dryness in these particular areas is a growing problem, especially when combined with the recent hot temperatures. Cooler temperatures in the short term should reduce stress levels somewhat with daily reference evapotranspiration rates that were as high as 0.23-0.28 inches per day the week of June 6 falling back to levels generally in the 0.15-0.20 range through Saturday. From a climatological perspective, seasonal rainfall deficits (since April 1) now generally range from about two to three inches in the Upper and northern Lower Peninsulas to as much as five to six inches in southwestern and south central sections of Lower Michigan. Note that normal rainfall for the same period in these areas is on the order of 7.0 to 7.5 inches.