Rhode Island Apple IPM
2002 - Current Pest Report - Visual
Tree Stage for McIntosh trees:
3/31/02 - green tip
4/13/02 - half inch green
4/15/02 - tight cluster
4/18/02 - pink
4/20/02 - bloom
5/6/02 - petal fall
8/9/02 - I didn't get to check many traps this week,
but apple maggot flies are still flying. If
it's been more than two weeks since you've sprayed, consider one more
- New York has reported second generation white apple leafhopper egg hatch.
I have not seen any white apple leafhoppers, but they should be around
in orchards that did not adequately control them at petal fall. Leafhoppers
can be controlled with a full rate of Sevin, but this is harsh on mite
predators. A better choice is to use Provado at 1/2 ounce per 100 gallons.
Provado has a 7 day pre-harvest interval.
8/2/02 - More apple maggot flies;
if it's been 2 weeks since you've sprayed, I'd advise spraying again.
7/26/02 - I do think we are at peak apple maggot fly
period. See RI chart.
- If you are using Thiodan to control leafhoppers, but sure to use it
at the full rate. Two growers have used it at half rate and had poor results.
7/25/02 - I thought I might catch a lot of apple
maggot flies after the rain on 7/23. I'm not. Perhaps there has not
been enough time since the rain. I'll check that Red Astrican tree with
the 7 traps tomorrow.
- Everything else looks good. There are a few more leafminers showing
up, but I don't see high populations anywhere.
- I forgot to mention it before: I participated in a survey of peach and
plum trees, looking for Plum Pox Virus. We sampled most peach orchards
in the state. All trees tested negative (Good thing!)
- Please contact me if you want me to collect a leaf tissue and soil sample
from your orchard. I hope to collect samples next week - so please let
7/19/02 - I caught more apple
maggot flies this week. On monitoring traps set up in many orchards
I caught about one per trap. On the 'Red Astrican' tree where I have 7
traps to trap-out apple maggot fly, I caught 210 flies this week! I also
have 8 traps set up in an 'Early William' tree to trap-out flies. I only
caught one fly on all 8 traps. I expected to catch more! If it has been
more than 14 days since your last insecticide application, I recommend
you apply one soon.
- European red mites and Two spotted spider mites have been building and
causing bronzing in some orchards. Two growers tried Vendex plus Silwet
or Tactic last week. In both situations the control was less than adequate.
I'm not sure what the problem was. In one situation the grower was probably
trying to spray too concentrated (I believe 6x). In the other situation
I don't know what went wrong. If you do have a high red mite population
(more than 7 per leaf), consider applying Pyramite. If your trouble is
two spotted mites, I still recommend Vendex plus Silwet or Tactic. Mixing
Vendex plus oil will probably give even better results, but if you use
oil, don't use Captan for at least 7 days.
- I've found wooly apple aphids in two orchards. I don't have experience
with wooly apple aphid problems. Every year I find some, but they never
seem to get out of hand. They may get out of hand at some orchards this
year. If you find too many (how ever many that is), apply Thiodan. Provado
will not control wooly apple aphids.
7/12/02 - I found a few more apple maggot flies this
week. I have 7 traps set up in one early ripening tree (Red Astrican -
sp?) that is not being sprayed. On these 7 traps I caught 70 apple maggot
flies or an average of 10 per trap. These traps are unbaited, but the
natural lure of the early ripening tree attracts the apple maggots. So,
apple maggot flies are around and at least are attracted to some early
varieties. Now would be a good time to apply an insecticide against apple
maggot flies, especially if your orchard received half an inch of rain
this past week, as many did on July 9. Half rates of Guthion or Imidan
control apple maggot flies well for two weeks, provided we get less than
two inches of rain. When more than two inches of rain fall, insecticide
coverage is probably inadequate to control apple maggot flies.
- I found a lot of rose leafhopper nymphs at several orchards this week.
If you find many, apply Provado at .5 ounces per 100, or use Thiodan or
Sevin. We don't have a good threshold for leafhoppers, but I generally
go by 25% of leaves with leafhopper nymphs.
7/5/02 - I did find one apple maggot fly on a trap
today. It was on a 'Lodi' tree. It was the only one I found out of 31
traps checked this week. The threshold for apple maggot flies is an average
of 2 per traps. I don't expect many apple maggot flies until we get a
thorough soaking with rain. When it is necessary to spray for apple maggots,
use half rates of Imidan or Guthion. Apple maggot flies are very easy
to control because they spend a lot of time lapping up water from leaves
- European red mites have been building in some orchards. I find even
more orchards with large numbers of predator mites. Where there are many
predators, a miticide is probably not needed.
7/1/02 - No apple maggot flies yet, and I've checked
quite a few traps. I'll write more on Friday.
6/28/02 - I've been setting up apple maggot fly traps
this week. I've only checked a few traps, but so far, no apple maggot
- White apple leafhoppers seem to be more numerous this week. Even where
Sevin was sprayed for thinning, I'm still finding white apple leafhoppers.
If your population is high, it is better to spray sooner rather than later.
The white apple leafhopper adults will lay eggs and these eggs won't hatch
until August. Delaying spraying the adults will allow more eggs to be
-Rose leafhoppers do not seem to be as numerous this year as most years.
Maybe they still will migrate over from roses, or maybe the population
is lower this year than it has been other years. The same chemicals control
white apple leafhopper and rose leafhopper: Provado (at 1/2 ounce per
100 gal.), Thiodan, or Sevin.
- I've only seen a few potato leafhoppers this year. These leafhoppers
tend to feed on the leaves at the tips of terminals. Feeding from potato
leafhoppers cause the terminal leaves to curl, and turn yellow or brown;
this stunts the terminal growth. This is not a problem on mature trees,
but is a problem on young trees where you want maximum growth. Guthion
or Imidan should control potato leafhoppers.
- This weather is perfect European red mite weather. The threshold red
mites for July is 5 mites per leaf or 76% of leaves with red mites. At
a few orchards I've found high numbers of mite predators! It is really
worth it to only use chemicals that are not harmful to mite predators.
6/24/02 - I was just with a grower who has been applying less than
half the amount of recommended chemicals, accidentally. This mistake can
easily be altered if you know how much water should be applied per acre
for a dilute application. Once the correct dilute application is calculated,
you can figure out how much water you actually apply and then see what
concentration you do spray. It is easy to calculate how much water needs
to be applied for a dilute application. You only need 3 measurements
to get tree row volume: tree height, tree width, and distance between
rows. Then you simply multiply tree height x tree width x (43,560
divided by distance between rows). Then there is just one more calculation
- take the number you just got (tree row volume) x 0.7 and divide by 1,000.
It really only takes a few minutes and it tells you so much! All this
is explained more completely starting on page 102 of your Pest Management
Guide. Please calculate your tree row volume so you know how much water
you should be applying per acre!
- White apply leafhoppers are present now as adults
and nymphs. These adults will be laying eggs, but these eggs won't hatch
until August. It seems much better to control white apple leafhoppers
now rather than controlling them in August. If you wait too long to control
this first generation white apple leafhopper, the adults will have laid
too many eggs and you'll need to control them in August as well. The bottom
line is to check now and control them now if you have a large population.
The white stippling damage is easy to see now. Look on older leaves and
on tree interiors for the damage. Provado, Thiodan, or Sevin control leafhoppers.
- Rose leafhoppers have been found in large numbers in only one orchard
so far this year. Remember, rose leafahoppers migrate over from roses
about this time of year. They migrate as adults (have wings and can fly/jump).
If you are finding nymphs now, they are probably nymphs of white apple
leafhopper. The same chemicals control both types of leafhoppers.
- Here is the mite weather we knew would arrive!
6/20/02 - I don't see any fresh plum curculio scars
in orchards where there was an insecticide applied since June 6. In unsprayed
orchards, plum curculio are still feeding and laying eggs. No more insecticide
should be needed against plum curculio, unless the last insecticide you
sprayed was earlier than June 6.
- Green apple aphids are present in most orchards now. I also see many
aphid predators or predator eggs in nearly all orchards. Rarely do aphids
require an insecticide application to be controlled. If for some reason
you do need to spray for aphids, use Thiodan, Provado or Sevin.
- I pulled a few dogwood borers out of the trunks of a few trees yesterday.
This orchard has a good herbicide strip under trees and the grass between
rows is kept short. Even with these clean conditions there were plenty
of dogwood borers. Dogwood borers appear to prefer 3-4 year old trees.
It is importan to check your trees, especially the 3-4 year old trees.
Trunk sprays of Lorsban control borers well.
- We haven't had weather that causes mites to build up, but it is probably
on the way. It is certainly better to apply miticides before mites cause
damage. Since this is true, check your trees now for European red mites
and two spotted mites. I've also mentioned yellow mites in the past. Yellow
mites look almost exactly like two spotted mites only they don't have
two spots. The damage they cause is similar to two spotted mites as well.
Both mites cause the leaves to turn paler or brownish, especially on the
lower leaf surface. At this time you can apply Apollo, Savey, Pyramite,
or Vendex plus Silwet or Tactic. Using Vendex is probably the cheapest
choice. Pyramite does not control two spotted mites well. I don't know
how well Pyramite controls yellow mites.
- I plan on setting up apple maggot fly traps next week.
- I've seen some blossom end rot in a couple of orchards, especially on
Macouns. There is nothing to spray now to protect the fruit. It will not
spread to other fruit.
6/14/02 -As I said on June 10,
insecticides should be applied since June 6 to cover to the end of plum
curculio season. In Newport and Little Compton, the final spray date for
plum curculio is June 16 - so after this wet weather another insecticide
application should be made.
- I saw one orchard today with a lot of white apple leafhopper. This orchard
did not receive Sevin for thinning. In another orchard I believe I saw
a lot of rose leafhopper adults. I think they are rose leafhopper because
I don't see nymph feeding damage and the orchard is practically surrounded
by multiflora rose. These rose leafhoppers will lay eggs and the nymphs
will need to be controlled later, probably in early July. Leafhoppers
can be controlled with Sevin, Thiodan, or low rates of Provado (.5 ounces/100
- Lorraine Los at the University of Connecticut reports finding San Jose
crawlers on June 11. I have not looked for any, but according to degree
day models, we expect to see first crawlers on June 17 in Greenville area,
and June 21 in the Newport/Little Compton area.
6/10/02 - Well, there's been
a change in plans. After last week's rain, insecticides applied before
June 6 were washed off and will not protect trees to the end of plum curculio
season. Plum curculio are expected to migrate into the orchard until around
June 13. If these late comers are not killed by insecticide they can continue
to cause damage for several more weeks. So, the bottom line is you need
to reapply an insecticide since June 6. This should surely be the last
insecticide necessary to control plum curculio. A border row application
would be suitable if your orchard is large enough to warrant just a border
- I found some leafhopper adults in one orchard today. Since I don't see
damage from leafhopper nymphs, I think these leafhoppers are rose leafhoppers
that are migrating into the orchard. They do not need to be controlled
now. Each year I seem to find more and more orchards needing to spray
for rose leafhoppers.
- Leafminers have been pupating in the mines and I expect the next generation
adults to be emerging in a week or so. When I open up mines sometimes
I am happily surprised to find a parasite rather than a leafminer larva
or pupa. In one orchard, 6 out of 12 mines I opened contained parasites
rather than the pest leafminer.
- Apple scab has been visible on fruit for at least a week now. Now is
a good time to check fruit to see if it is scab-free.
- There are plenty of green apple aphids present on terminals, but there
are also plenty of aphid predators. I don't anticipate anyone needing
to spray for aphids.
I'm seeing more scab! I do see a few orchards where there is just a bit
of scab, but more orchards have serious scab problems. I only see a few
orchards that are scab-free! If you have just a little bit of scab, use
a full rate of Captan. If you have a lot of scab use Sovran or Flint.
- Plum curculio have been very active over
the past week. I see a lot of egg laying scars in unsprayed trees.
- Leafminer are showing up a bit more now that they are visible from the
upper leaf surface. I still don't see any orchards with leafminers that
are above threshold. Leafminers have begun pupating in the mines and will
begin emerging as next generation adults in a week or so. Now is not the
time to control leafminers.
- I see some green apple aphid colonies forming on newest foliage. I also
see predator eggs (white syrphid fly eggs and larvae) nearly everywhere
there are aphids. Hopefully no one will need to spray for aphids since
predators usually control the aphids adequately.
- Powdery mildew is showing up in some orchards. Now is not the time to
spray for powdery mildew (it needs to be controlled at petal fall and
first cover). There is nothing you can do about it now so don't try spraying
for it now.
5/29/02- There has been a lot
of plum curculio activity the last few days. Everyone should be well protected
with an insecticide. Insecticides applied now should control through the
end of plum curculio season (except in the Newport & Little Compton
area where sprays need to be applied through June 4 to completely cover
plum curculio season.)
5/27/02 - I saw two
more orchards with lots of apple scab today! Ugh! Scout your orchard now
and spray with Sovran or Flint if you find more than a little bit of scab.
- I saw many new plum curculio bites in an unsprayed orchard today. I
expect this week to be peak plum curculio activity for the season. If
it has been more than 7 days since your last Imidan or Guthion application,
consider applying one soon. Sometimes a single unprotected evening can
allow a lot of damage if conditions are right (warm, humid evening with
- European red mites have begun laying summer eggs.
- It is too late now to treat for first generation leafminer mines. As
I said before, I do not see many mines in any orchards. this year really
seems to be a light year.
5/24/02 - I am so sorry to announce that
Keith Harbert died yesterday (5/23). We will miss him dearly.
- I see a lot of apple scab at several orchards. I mostly see lesions
on the top side of middle aged leaves. If you find more than a little
bit of scab, consider applying Sovran or Flint. Even though we are at
the end of primary scab season, the spores from scab lesions can easily
spread this time of year. Leaves and fruit are very susceptible to scab
now and for the next two weeks.
- I see some very old (~2 week old) plum curculio scars and a few new
(last couple of days) plum curculio scars. If we get thundershowers tonight,
we could see a lot of plum curculio injury. Above 80 degrees and humid
conditions, especially in the evening, are perfect for plum curculio.
- I found my first leafminer mine that has advanced to the tissue feeding
stage. This is when the mine is visible from the upper leaf surface. If
you are planning on applying AgriMek, it needs to be applied now.
- I am surprised how few leafminer mines I have seen this year. Perhaps
the cold/wet conditions earlier this season inhibited much leafminer egglaying.
5/23/02 - Sorry I haven't written earlier this week.
-We should be at the end of primary scab season now. It is still advised
to keep your trees protected with fungicides for the next 2 weeks. This
will protect leaves and fruit from scab spores spreading from lesions
that may be in your orchard. Leaves and fruit are extremely susceptible
to scab for the next two weeks.
- I have seen scab lesion in 3 orchards. Check your orchard now for the
olive green/brown lesions. If you find more thatn a few lesions consider
applying Sovran or Flint. The next best choice would be Rubigan, Nova,
- I have seen a few plum curculio scars, but these have all been old scars,
made soon after petal fall. and I have seen very few. I will check many
orchards tomorrow for damage. This warmer weather should stimulate them
to feed and lay eggs.
- I have seen many white apple leafhoppers in one orchard. This orchard
had at least 1/leaf. There isn't a good threshold for WALH, but some researchers
have suggested 1/4 leaves. Sevin, Thiodan, and Provado should all control
- Yesterday I found one apple with the tiny trail caused by a European
apple sawfly larva. If EAS are not controlled by an insecticide, the larvae
enter a second fruit and tunnel down to the core. I rarely see this in
a commercial orchard, but they are extremely common in unsprayed trees.
5/15/02 - We did have quite a severe apple scab infection period starting
on 5/12 and continuing through 5/13. More than 50% of the season's ascospores
could have been released during that wet period. The good news is that
we are close to the end of primary apple scab season. In one week or less
we should be at the end.
- Leafminers can easily be seen from the underside of leaves now (Relatively
easy - not easy the way they can be seen from the upper leaf surface).
Look now for leafminer mines and treat with AgriMek if you find more than
13 mines per 100 cluster leaves. Remember, AgriMek must be mixed with
something that can make it penetrate the leaves. It must be mixed with
oil or a surfactant such as LI 700.
- Plum curculio may have moved into orchards over the past few weeks,
but they have not started their feeding or egglaying. I don't expect much
(if any) plum curculio damage until it warms up over 70 degrees.
Growers who have not applied an insecticide yet this year are probably
in fine shape.
5/10/02 - I did catch 19 European sawflies per
trap at one orchard today. I thought sawflies were not around this
year, but apparently they are in some locations. Nineteen per trap is
still lower than we usually catch.
5/9/02 - It looks like we may slide by an apple scab infection period
today. If the rain holds off until after sundown and then it dries up
tomorrow morning, it will be perfect. Ascospores would not be released
until day break - and then the spores would dry out and die. This would
be a great way to get rid of ascospores that have been maturing but not
released over the past week. Approximately 77% of overwintering scab ascospores
have matured by now. We expect the end of primary scab season in about
- Plum curculio are not active in this cool weather and it looks like
no real warm weather is in sight. Plum curculio prefer 80 degrees and
humid conditions. At this time there is not a need to apply an insecticide
against plum curculio.
- If you are applying Provado against leafminer, you should apply it at
petal fall to get the most thorough control.
5/6/02 - The warmer weather over the last few days has pushed McIntosh
trees into petal fall in most areas (not east of Narragansett Bay). Many
varieties, such as Cortland and Macoun, are still at full bloom.
- We usually get huge numbers of European apple
sawflies in most locations in Rhode Island. I've only checked traps
at a few locations, but the trap captures are very low. This means you
probably do not need to rush out at petal fall and apply an insecticide.
Instead you can wait to apply an insecticide until it is more likely plum
curculio will be active. Plum curculio tend to be active when temperatures
are above 75 degrees. They especially prefer humid conditions. I've heard
very conflicting weather reports. Some reports forcast hot and humid weather
and other reports say cool and seasonable. If we do get hot humid weather
then plum curculio could cause damage this week.
- If we do get wet weather that causes an infection period this week,
it could be a major infection period because so many ascospores
would be released. Now is not the time to skimp on fungicides.
5/2/02 - Today is probably our second apple scab infection period
of the season. It is averaging 46 degrees and at 46 we need only 16 hours
of wetness for a slight infection period, or 21 hours for a moderate infection
period. See Mills Table.
- We still have approximately 60% of overwintering spores yet to mature
and be released, so we still have plenty of primary apple scab season
ahead of us.
- Cedar apple rust galls are active during wet weather now till mid-June.
Varieties that are susceptible to cedar apple rust should be protected
before rain events. Rusts cannot be managed with post-infection sprays.
The mancozebs (Manzate, Dithane...), Polyram, and the sterol inhibiting
fungicides (Rubigan, Nova, Procure) all give excellent control against
rusts. Captan has only slight activity against rusts.
- I caught a few European apple sawflies last week, but none this week.
It looks like this cold weather is keeping them inactive.
4/29/02 - We are finally having our first apple scab infection period
of the season.
- Cold temperatures last week and especially Saturday morning (4/27) have
damaged buds/flowers/fruit. The coldest I heard from an apple grower is
24.5 degrees. Perhaps the damage won't be as bad as last year because
it didn't remain cold as long as it did 5/7/02.
- Cedar apple rust fruiting structures visible on cedar trees. Apple
trees are susceptible to infection now.
4/25/02 - I still don't think we have had an apple scab infection
period yet this year. Perhaps we will today, but I think not. It is cold
and getting colder, and should dry up early tomorrow.
- I am having a hard time finding European red mite eggs or nymphs. I
am finding many mite predators - Z. mali. Some orchards are really loaded
with the little yellow predators and I can find 4 or 5 per leaf.
- According to the SkyBit insect models, there should be hatched leafminers.
I've only seen eggs, not hatched leafminers yet. I haven't seen very many
eggs so I'm probably missing the hatched ones.
4/22/02 - It looks like it will be too cold to cause an apple scab
infection period today. At 39 degrees you need at least 33 hours of leaf
wetness to cause an infection. If the weather says wet through tomorrow
there could be an infection period.
- I checked red sticky traps at 2 orchards for leafminers. The traps were
not set up until 4/18 and I only caught 1/trap. I don't think this information
is very valuable since the traps were set up so late.
4/20/02 - I checked a few more red sticky traps today for leafminer.
At two orchards there were very few leafminers. At a third orchard there
were 3 traps with zero and one trap with about 200 leafminer adults! What
variability! That makes an average of 50 leafminers per trap at that orchard
(and above the threshold of 21 leafminers per trap by pink).
- Saw 2 of the new yellow pest mites, Eotetranychus carpini borealis,
in one orchard, as well as many Z. mali predator mites. This is
the first time I've seen these yellow mites this year.
- Rain began around 4:30 this afternoon and it looks like it will stay
wet through the night. If this does happen, it will be our first infection
period of the season.
- I found 15 tarnished plantbugs on one trap
today. That is the most TPB I've seen on one trap for many years. The
threshold at this orchard is still below the threshold of 8 per trap,
but I am concerned about TPB this year. The white sticky traps work well
up until about tight cluster, then I am not certain how well they perform.
4/19/02 - Yesterday I found one or two hatched European red mites.
This is not surprising since we are already at pink. Reduce oil applications
to 1 gallon per 100 gallons of water.
- Leafminers are very high (64/ trap) at URI's East Farm, but we have
caught none at different orchard. I hope to check more traps tomorrow.
- I saw my first leafminer eggs yesterday; I only found 2eggs - but they
have started laying.
- I saw 2 species of mite predators yesterday: the yellow Z. mali
and a pale one, either A. fallacis or T. pyri. Don't use
a synthetic pyrethroid (such as Pounce) and killl your predators.
- The most tarnished plant bugs I've found on one trap is 5, with an average
of 2 per trap in that orchard. Plant bug captures are below threshold
in the two orchards checked so far.
4/15/02 - Yesterday I saw my first tarnished plant bugs on apple buds.
I don't have many white sticky traps set up yet, but I do have three traps
at URI's orchard: East Farm. At East Farm today I found one TPB on one
of the three traps, or .33 TPB per trap.
- Leaf miner - I caught 57 leafminers on 3 traps set up at East Farm on
4/12. This exceeds the tight cluster threshold of 8 leafminers per trap
by quite a bit. The mild winter may have allowed many leafminers to survive
over the winter.
- I saw many Asian ladybugs in orchards yesterday.
- I saw pear psylla adults and eggs on pear twigs yesterday.
- Many growers have been applying oil and a fungicide when the wind dies
- I don't think we have had a true apple scab infection period since there
have been more than 10% mature ascospores ready for discharge. (10% is
the threshold where we start worrying about infection periods). If we
begin measuring today's wet period from 8:00 AM, apple scab spores would
have needed 6 hours of wetness to cause an infection.
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