5. Blossom
End Rot-How is it caused and how to reduce incidence
Causes
and Remedies for Blossom End Rot in Peppers, Tomatoes, and other Solanaceous
Vegetables
Blossom end rot is a
physiological disorder caused by factors other than pathogens or insects. In
1914 Brooks described blossom end rot in tomato in the journal Phytopathology but did not explain its
exact causes. The disorder appears as a water-soaked region, often chlorotic,
on the blossom end of large fruited varieties of tomato, pepper, eggplant,
watermelon and zucchini grown either in the field or in greenhouses. Symptoms
of blossom end rot usually occur within two weeks after fruit set. Blossom end
rot symptoms usually occur on the earliest fruits but it can also occur on
later fruits if conditions are favorable. Long fruited varieties are more
vulnerable to blossom end rot than round fruits, but it can also occur on round
fruits as the following photo illustrates. However, no blossom end rot symptoms
have been seen on wild tomatoes and they rarely occur on small fruited
varieties like cherry tomatoes. The disorder can also occur on the inside of
the fruit in the tissue surrounding the seed where it is called “black
seeds.” The incidence of blossom end rot is infrequent in most properly
managed fields, but it can be very serious under certain conditions. Tomatoes
showing blossom-end-rot.
Since 1942, most experts
have agreed that the disorder is likely caused by calcium deficiency in the
distal end of the affected fruits. However, there are other factors that have
also been linked to blossom end rot incidence, including low tissue phosphorous
and manganese, high tissue nitrogen, magnesium, and potassium, high soil
salinity, drought stress, too much water, high temperature, high light
intensity, location of the fruit on the plant, root damage, and cultivar. Most
of these factors, however, appear to affect plant growth and so their effect
may be indirectly related to the incidence of the disorder compared to calcium.
Calcium controls the process of cell expansion and serves as a messenger for
cell to cell communication. Calcium is delivered into the fruit via the xylem
vessels. There are fewer and narrower xylem vessels at the blossom end of the
fruit where the rot is likely to occur. Also the xylem to phloem ratio is low
and there are fewer vessels in the seed cavity in the blossom end of affected
fruits. Combined, these factors are believed to be the reason why the rot develops
on the blossom end of the fruit. Before you jump on your tractor and start
spraying the plants you need to be aware that blossom end rot is not a simple
disorder that can be cured with calcium for many reasons. Studies have shown
that there is no critical level for calcium that can induce the rot, other
elements beside calcium can also contribute to the rot development, and some
hormones and high temperature have also been shown to induce the rot. Even when
assuming that calcium is the main reason for the rot, some fruits like tomato
are not likely to respond to calcium treatment. Tomato fruits do not have
openings (stomates or lenticels) on their skin and so it is difficult for
calcium to move through the skin and into the fruit, especially during the critical
times at the early stages of development. Here are a few tips on how to prevent
blossom end rot from developing in your tomatoes, peppers or other fruits.
1. Check soil pH the
previous fall before planting and add non dolomitic lime to correct low pH.
2. Check the soil organic
matter. Subtract the amount of nitrogen in the soil from the total amount of
nitrogen that the plants
need for optimum growth.
3. Avoid adding too much
Mg, K, or other cations that compete with calcium unless the plants show visible
signs of deficiency.
4. Do not use ammonia
type fertilizers, use nitrate forms instead. Ammonia fertilizers compete with
calcium uptake.
5. Choose cultivars that
grow slowly, produce less foliage, and produce medium size fruits. Cherry
tomatoes do not develop blossom end rot.
6. Avoid planting too
early in the season.
7. Do not severely prune
the plants.
8. Avoid damaging the
root system by cultivating away from the plants.
9. Adding too much
nitrogen, especially early in the season will likely lead to blossom end rot
development.
10. Maintain adequate
soil moisture. It is better to irrigate frequently at low rate than to irrigate
once at high rate.
Spraying calcium,
regardless of its form, will not eliminate blossom end rot on affected fruits.
The three most important factors that will likely minimize blossom development
in your tomatoes, peppers or eggplants are to monitor the level of nitrogen
carefully
(divided the rate into
smaller doses and use nitrate nitrogen), prevent fluctuation in soil moisture,
and keep the soil pH at 6.5 to 6.8. If you can manage these three factors, you
can manage blossom end rot.
6. Corn
Ear Worm Control
If/when/where corn
earworm control in tomatoes is necessary (remember that corn earworm also is
known as tomato fruitworm) Bacillus
thuringiensis (Bt) products are fairly effective. They work against
this insect in tomatoes but not against it in sweet corn because in tomatoes
the larvae feed on some on foliage and the surface of fruit, where they ingest
Bt spores and toxins that poison them. In sweet corn they do not feed until
they have entered the silk channel, never consuming any plant tissue that has
been treated with Bt sprays. Bt products and Entrust are effective alternatives
for organic growers.
Email Recd Sat 8/24/07
By Dr. Chris DeFonzo MSU Dept of Entomology
Quick take home messages:
* Aphid numbers are increasing in the eastern Great Lakes area, dramatically in
some locations
* For the week of August 6th, if you haven't already, check fields this
week for aphids, especially late-planted fields. Even a quick walk into the
field will alert you to a problem. Some places will have low or no aphids, but
you may find some surprises.
* Think coverage, coverage and COVERAGE
Last week I said not to ignore aphids just yet... and sure enough ALL
%*#%*@% HAS BROKEN LOOSE in the last few days. Bottom line,
aphid numbers in many locations in the eastern great lakes area have come up,
including locations in Michigan. I know this message is long, but I wanted to
do my best explain and summarize the many observations so you are ready for the
upcoming week.
Early last week (July 23-25), a front moved west to east across the Great
Lakes. The circulation was counterclockwise, in other words winds moved south
to north at the east edge of the front, back to the west, then north to south
at the back of the front. If you looked at the radar picture on Tuesday July
24, the spotty rain showers in Michigan were moving north to south in a
straight line as the back of the front crossed the state.
As the front moved east, the eastern edge passed over areas (New York and
Quebec) heavily infested with SBA. My colleague Michelle Roy in Quebec has had
a big SBA infestation this year, and she reports that 90% of the acres have
been treated in southwestern Quebec. The front presumably picked up winged
aphids, circulated them back to the west and then south, dropping them with
rain on the back edge. As a result, fields probably received large number of
winged aphids from NY and Quebec that started infestations - sort of like
sparks coming off a forest fire.
Below are summaries or quoted parts of messages from colleagues in MI and other
states. All of these messages are from Friday Aug 3rd, obviously a key
aphid day. They illustrate how quickly aphids can infest an area.
SUCTION TRAP COUNTS: Captures of winged aphids increased dramatically the
weeks of July 16 and 23 in the aphid suction trap network ( http://www.ncpmc.org/traps/index.cfm),
especially in Minnesota and Wisconsin. There are no traps on the network to the
east of MI, but I assume Quebec and New York had big flights too.
Martin Nagelkirk, Sanilac County MICHIGAN: "...a CPS fieldman
and farmer found aphids at threshold along Lake Huron". Likely
fields in neighboring counties are infested too. Insects of many types often
rain-out along the edges of the Great Lakes.
Phil Kaatz and myself, Lapeer Co. MICHIGAN: Phil and I found a field with a
healthy new infestation on Aug 3, north of Lapeer city. The field was clearly
newly colonized - each plants had 2-5 moms (probably sisters deposited by the
same winged aphid a week ago), and each mom's tiny new babies. This field
was late-planted, R2 stage, and the aphids were infesting the juicy top part of
the plant. An infestation like this can be over threshold in 7-10 days.
Scott at Napolean Feed Mill in Jackson Co MICHIGAN: "I am seeing over
threshold numbers of aphids in the Springport, Parma, and west of Jackson area.
...I'm not finding aphids in all fields, but the fields I am finding them in
seem to be over threshold." Remember that there are also
reports of potassium deficient fields going over threshold in southern Michigan.
NEW YORK, Keith Waldron, Cornell Univ: "Over the past 10-14 days SBA
populations in Cayuga, Chemung, Columbia, Cortland, Oneida and Seneca counties
have increased dramatically with numerous fields exceeding the recommended
threshold... some fields treated earlier this season for SBA are again at or
over threshold." Keith reports fields outside these counties are
below threshold, but increasing.
Ron Hammond, OHIO STATE: "NE OH definitely has problems. Saw
numerous fields having reached threshold, few somewhat over threshold, one
field where plants were fully covered with aphids and sooty mold and honey
already getting heavy. Haven't seen that since 2005. Surrounding
counties have them on the rise nearing threshold. ...From others around the state,
have heard aphids are showing up, but no where near what the NE section of OH
has"
Missy Bauer w/ the Andersons, Pioneer OHIO (just south of Michigan)
- Missy reports numbers near her house have "increased
dramatically" in the last two weeks. Her latest count averaged almost
150/plant.
Tracey Baute with OMAFRA in ONTARIO: "I have heard from some key reps
today that they have fields that had very low to nearly no aphids last week to
10 days ago, now have aphids above threshold. In particular an area that
has really exploded is in Niagara and Haldimand Counties, close to Buffalo
NY. Some other fields scattered across the province will be sprayed in
the next 7 days as the beneficials have lost the battle."
Tracey also adds an important caution about rebounding aphids and spray
COVERAGE: "We've had some fields sprayed 2 to 3 times with aphid
populations rebounding within 10 days..... Spray coverage is probably the
biggest issue for these guys now".
Remember the 3 most important things when spraying for aphids = coverage,
coverage and COVERAGE!
***A BIG Thank you to everyone who calls or emails me with reports of insect
infestations and numbers. The reports help to get a big picture of what is
happening****
chris
<><><><><><><><><><><><><><><><><>
Dr. Christina DiFonzo
Field Crops Entomology Program
Michigan State University
East Lansing, MI 48824
Mailing Address: 243 Natural Science Building
Office Address: 331 Natural Science Building
tel: 517-353-5328 fax: 517-353-4354
<><><><><><><><><><><><><><><><><>
Greetings Sustainable Agriculture Network Discussion
Group:
As part of a larger research study, I have developed a questionnaire
that seeks your opinions and views on the topic of pollinators in
agriculture. I am gathering information from agricultural producers,
land managers and scientists. I would like to ask you to take a few
minutes to participate in the study by completing an online questionnaire
that takes 5-10 minutes to complete. Your answers will be kept
confidential and information gathered from the questionnaire will be pooled and
not linked to any individuals. At the completion of the study, results
will be available upon your request. The questionnaire is online at
a web-based survey service, SurveyMonkey.com.
To access the questionnaire, please click the following link:
http://www.surveymonkey.com/s.aspx?sm=n9bGeFsu2zxrwZbRAgdDUg_3d_3d
If you have any questions, comments or concerns, please feel free to
contact me. Thank you in advance for your assistance!
Best regards,
Annette Meredith
*(************************************************
On 7/30/07, JONATHAN
SOLIS <[log in to unmask]> wrote:
> > The South Side Community Coalition is
still looking for
> > farmers/vendors
to sell their produce/products in the Southwest area
> > of Lansing.
This area is in need of fresh fruits and vegetables.
> > Also, we have a
high usage of EBT and Project Fresh Coupons clients.
> > We will be
accepting EBT (electronic benefit transfer) as well as Project Fresh Coupons.
> >
> > NO FEE TO USE
SPACE
> > EVERY TUESDAY
2PM TO 6:30PM
> > SET-UP TIME IS
FROM 12:30 TO 2PM
> >
> >
Location/Contact Number
> > 2101 West
Holmes Rd
> > Lansing
Michigan 48910
> >
Solis: 517-394-6846 Wk
>
> 517-393-3547 Hm
> >
Lisa: 517-394-3217 Wk
> >
Email: [log in to unmask]