What’s New and Exciting for the Greenhouse Industry in 2004/2005?
New Products, Natural Enemies and Techniques for the IPM Practitioner
As Presented at the New England Greenhouse Conference
Worcester, MA, October 20, 2004
Michael Brownbridge
University of Vermont, Entomology Research Laboratory
Traditionally, this session has primarily focused on pesticide developments. But, if we
are to make progress towards the broader implementation of IPM in production greenhouses,
then we need to consider a wider range of materials and techniques. So, although pesticide
updates will be included in this presentation, information on other developments that are
pertinent to the successful production of healthy plants, and the utilization of a variety of IPM
techniques will also be included. This will include scouting/monitoring and cultural
considerations, biological control agents, bio-derived products and botanicals, and new pesticide
information – including label changes, new packaging, and new products.
The first goal of any crop protection program should be the production of healthy plants.
Thereafter, should pest problems develop, they are likely to be less severe, the plants more
tolerant of, and able to recover from, any damage caused, and the crop ultimately more saleable
at the end of the production period. However, constant attention needs to be paid to the health of
the crop, and to the early detection of pests and diseases. Early detection facilitates early
treatment, and greater opportunities to utilize reduced risk materials and biological controls.
In terms of pest monitoring, traditional tools such as yellow sticky cards are unchanged,
and nothing beats getting into your crop and scouting the plants, but there is increased interest in
the use of “trap” or “sentinel” plants for pest detection. Some plants appear to attract insect
pests; our own research suggests that certain marigolds, for example, seem to work very well in
this capacity for thrips, aphids and mites, and we will be testing these in commercial greenhouses
in the coming spring; verbena have been similarly assessed in Europe. Such plants may prove to
be viable early-warning indicators for several pests, and the information used to guide pest
management decisions. They might also be useful as banker plants, something that will be
covered later in this presentation.
To complement regular scouting activities, diagnostic tools such as AgDia ImmunoStrips
are extremely useful; these are available for a range of common plant diseases and allow the
health of incoming and outgoing plant shipments, and crops, to be quickly assessed, on-site. The
most recent addition is a test strip for Clavibacter michiganensis subsp. michiganensis, the
causal agent of bacterial canker in greenhouse and field tomatoes. Also relatively new, are the
combo strips, primarily for plant viruses – you can get a strip for INSV/TSWV, and combs that
test for Cucumber mosaic virus, INSV, TSWV and tobacco mosaic virus all at the same time.
These are a more expensive option, and probably not appropriate for many smaller growers, but
individual test strips (e.g., for INSV) can play an essential role in any IPM program. Agdia
recently sent out letters indicating that a cross-reaction to TSWV could occur with the INSV
immunostrip test; while this does not limit the tests’ ability to detect INSV, false positives could
occur. However, both tospoviruses are vectored by thrips, neither can be cured, and TSWV is
rarely a problem in ornamentals.
Not often talked about in relation to pest management, but water quality – pH and water
hardness – can have a major impact on plant quality and pesticide performance. Firstly, many of
the new plant varieties grow best at low pH (around pH 5), so their general health will be
adversely affected if grown under alkaline conditions. Secondly, the efficacy of many pesticides
is adversely affected by exposure to alkaline spray water, or they can be inactivated in hard water
with high levels of Ca, Mg and Fe – Floramite for example is rapidly degraded in alkaline water
– which affects their residual performance. Test the pH and hardness of your water regularly. If
need be, there are a number of ways and products that can be used to achieve the optimum range.
Griffin sells a product known as pHase 5, for example, which counters effects of high pH and
hard water on sensitive pesticides.
On the biological front, there are a few newish developments and products, and natural
enemies to look for. On the nematode front, Nemaslug – is a not-so-new nematode-based
product based on a strain of the mollusc-pathogenic nematode Phasmarhabditis hermaphrodita;.
These aggressive nematodes actively seek out and attack slugs, killing them within 7-10 days of
invasion. Nemasys H is a newer product based on the insect-pathogenic nematode
Heterorhabditis megidis; it is sold for black vine weevil control. Both are produced by BeckerUnderwood and sold through AgBio, Inc. BioWorks, producers of Plantshield, recently
announced a new and improved formulation for their product Nemashield, which contains the
nematode Steinernema feltiae, which can effectively control fungus gnat larvae. The new
product is formulated on a water-dispersible carrier, and is available in two sizes, containing 50
or 500 million infective nematodes. Remember, each nematode species has a limited host range,
and these 3 products are intended for use only against the pests listed on their labels.
On the predator front, the rove beetle Atheta coriaria has provided excellent control of
shore flies when released at 100 beetles per week per 5000 sq. ft of greenhouse. These trials
were run an a large commercial greenhouse, with releases being made in the cooler mornings or
evenings when the beetles are less likely to fly. While their preferred diet is shoreflies, they also
feed on fungus gnat larvae and pupating thrips.
Long used as incubators for the production and delivery of beneficial species in
greenhouse vegetable crops, banker plants are again receiving attention for use in ornamentals.
Several parasitoids are being raised on banker plants, e.g., Aphidius for aphid control, Encarsia
for whitefly control. In such cases, the host insects reared on the banker plants are not pests of
the crop plants, e.g., grain aphids on barley, turnip aphid on cabbage; these are parasitized and
the emerging parasitoid adults will fly into the ornamental crop to search for and parasitize or
feed on new hosts, this time aphid pests on the crop itself. The aphid and parasitoid colony is
maintained on the banker plant, providing a slow and constant feed of parasitoids into the crop.
Some predators may also be reared on banker plants, e.g., Orius for thrips control, surviving on
the pollen in flowering banker plants such as marigolds, or on low numbers of pests which also
reside there. This technology has a lot of potential benefits for greenhouse growers, so you
should expect viable systems to become available before long.
On the microbial side, Earth BioScience registered a strain of the insect-killing fungus
Metarhizium anisopliae for control of the black vine weevil. The fungus is not yet available in
the US, but was very effective against BVW and had long residual activity in trials carried out in
container nurseries in Oregon. BotaniGard, based on the fungus Beauveria bassiana, has been
around for a number of years, providing a useful rotational product for whiteflies, thrips and
aphids; according to Whitmire, when used in conjunction with Pyreth-It, it is a useful clean-up
combination at the end of the spring bedding plant season, and can be used on blooms, herbs and
veggie transplants.
For soil borne diseases, although BioWorks PlantShield HC (a higher potency
formulation of the antagonistic/parasitic fungus Trichoderma harzianum T-22) has been around
for a while, you may have missed this. There is an easier way of getting this product into
suspension for application: put the amount of PlantShield you need into a plastic bag, add
sufficient water to make a slurry, twist-tie the bag closed and then shake vigorously, breaking
any clumps apart by pinching through the bag. Pour the mixture into your stock tank or bucket
and rinse the bag into the container; add the remaining amount of water needed. This simplifies
the process of getting the product into suspension, and also eliminates dust when mixing. Just be
sure to use a heavy duty plastic bag! Based on a strain of Streptomyces bacterium, Mycostop is
another product that is useful in the control of diseases such as Alternaria, Botrytis, Fusarium,
Rhizoctonia and Phytophthora; Mycostop Mix is a newer formulation that has been developed
for drench and seed treatment applications. The product is OMRI listed, and with a recent price
reduction and availability in two package sizes, it is now more affordable and amenable to the
smaller grower.
There are various bio-derived products that have recently come on to the market that are
classified as minimum-risk pesticides. These are exempted from product registration
requirements, even in New York State! Include are products such as: E-Rase (Jojoba oil) which
is sold for whitefly control on poinsettia; GC-Mite (cotton seed and clove oils, garlic extract) for
mites and thrips; Hexacide (rosemary oil and mineral oil); Orange-Guard (citrus seed extract) for
aphids and mites; Organocide (sesame oil) for aphids, mites and powdery mildew. There is very
little efficacy data available for any of these pesticides. A general word of caution: several have
produced phytotoxic effects on plants like poinsettia, so test them on a limited number of plants
first, and observe the response before treating a whole greenhouse. More information on
performance should become available in the coming months from Dan Gilrein of Cornell
Cooperative Extension, who is currently running greenhouse trials on many of these materials.
Azadirachtin – neem – is a better-known botanically-derived pesticide with proven
efficacy against a number of greenhouse pests. Ornazin is the most recent addition to the suite of
neem-based products, and is reported to have a longer shelf-life than its main competitors.
Olympic will be marketing a re-vamped Azatin in 2005; the new product will contain 4.5%
azadirachtin and be called Azatin XLT. The product will be OMRI listed, but its REI will go
from 4 to 12 hours because of the solvents used in the formulation.
So what’s new with chemical pesticides? Let’s start with the insecticides. There are
several reduced-risk materials heading on to the market, and this seems to be the way
manufacturers are going these days, as older insecticides are disappearing from the market.
Included in this are several new competitors for Whitmire’s Ultra-Fine Spray Oil. Synergy
Super Fine spray oil emulsion is manufactured exclusively for Griffin, and is labeled for mite,
insect and disease control on ornamentals. It carries a 4h REI and is fairly soft on beneficials, so
it fits well into an IPM program. It is produced using a micro-emulsion process which yields
smaller oil droplets; this promotes the formation of an emulsion when mixed with water, so that
the oil will stay in a uniform suspension for up to 3 h, unlike other spray oils which need
constant agitation. A second emulsifier promotes spreading and sticking, enhancing coverage
and activity while promoting adhesion to the leaf surface, extending disease protection. A third
emulsifier protects against UV; this reduces the potential for leaf burn, and affords protection to
pesticides tank-mixed with Synergy that are susceptible to UV degradation. Petro-Canada have
obtained EPA registration for another petroleum oil – Purespray Foliar-15 (Purespray Green for
the greenhouse?). This is currently registered in Canada for use on tree crops, fruits and
ornamentals, and they are looking to have it labeled for greenhouse use in the US. It is also
apparently OMRI listed.
Let’s move on to the more confusing world of the neonicotinoids. The list of Marathonlike products continues to grow. These compounds are all expensive, but provide long residual
control, have excellent plant safety and low mammalian toxicity, allowing them to be classified
as reduced-risk pesticides. They come in a variety of formulations, for application as sprays, and
in some cases, drenches; they have systemic or translaminar and contact activity, and are active
against a wide range of piercing/sucking insects. They vary in their activity against other insects,
such as caterpillars and beetle pests, so be sure to consult the label rather than assuming that they
are all the same; many are highly toxic to bees if used as a spray treatment on blooming plants.
Generally-speaking, they have similar modes of action, so cross-resistance to different products
is possible. As a result, products classified as neonicotinoids should not be used together in a
spray rotation. Chemicals with a different mode of action need to be used (e.g., an IGR).
Let’s start with 2 products that are actually on the market in the Northeast already, with
the exception of NY. Foliar sprays of Flagship (Syngenta) will control aphids, whiteflies, soft
scales, mealybugs, etc., and it is also recommended for HWA on hemlock. Drench treatments
may be used against Japanese beetles, chafer grubs, June beetles, etc. Foliar treatments are
rapidly absorbed, with noticeable effects in 24-48 h; soil treatments may take 2-3 weeks to show
an effect. Excellent plant safety, including blooms. The product has a 12 h REI, and
recommended rates obviously vary according to the spray volume, or type of treatment; it is
likely that the drench rates will be modified soon to improve efficacy against soil pests.
Resistance management: do not re-apply within 7-d; rotate with chemicals with different modes
of action; limit the number of applications in each growing season. Tri-Star (Cleary’s) is
formulated as a wettable powder in water-soluble packets for spray application only; a 20WP is
under development, which will make the product more amenable to smaller operations.
Currently labeled for use on nursery and greenhouse ornamentals against whiteflies, aphids,
caterpillars, sawflies, and others. Cleary’s are seeking a label expansion to add thrips, scales,
leafminers, Japanese beetles, and others. Foliar treatments are quickly absorbed, providing
protection from photodegradation and 2-3 wks residual control. The product currently has a 24 h
REI, but the company is seeking a 12 h REI. Rates vary according to the pest, and it is tank-mix
compatible with most other insecticides. However, it should not be used with adjuvants such as
stickers, but a spreader such as Capsil (Griffin) is fine. Resistance management: do not re-apply
within 7-d, no more than 5 applications per year.
Three neonicotinoid products that will be available, probably in early 2005, are Safari
(Valent), Clutch (Arvesta) and Arena (Arvesta). Safari received EPA registration in August, and
is labeled for use against aphid, whitefly and mealy bugs on ornamentals in greenhouse, nursery
and exterior landscapes. Works very well vs. mealybugs. It is not active against grubs, so will
not be marketed for grub control in lawns. It can be applied as a spray or a drench, and has a 12
h REI. Clutch is currently undergoing registration for use against a broad range of foliar and soil
insects in potatoes, apples and pears. It is already registered in Mexico. It is likely that a
greenhouse label will be sought in the near future, but the product is likely to have another name
in the US – possibly Arena.
What about products to use in rotations with these materials? In addition to the oils, you
may consider using an insect growth regulator (IGR), and there are several new low-risk
products that are available. Talus (Sepro) is labeled for use against whiteflies, mealybugs, and
scales on greenhouse and landscape ornamentals, container-grown ornamentals, and Christmas
trees, as well as greenhouse tomatoes. It is a chitin synthesis inhibitor, but also suppresses
oviposition and causes sterility in treated adults. It is applied as a foliar spray, with activity upon
contact or ingestion; no systemic movement, but vapor activity improves coverage. It has
excellent plant safety, and is compatible with many beneficials. It is packaged in water-soluble
bags, and the rate used depends on the target pest; it is tank-mix compatible with most common
insecticides. The product has a 12 h REI. Resistance management: no more than 2 consecutive
applications with 14-28 d re-application intervals; mode of action similar to Adept, Citation and
Pedestal, so do not rotate with these products. Pedestal (Crompton Corp.) is now registered in all
Northeast states except NY for use on containerized ornamentals, and is very effective against
thrips, whiteflies and leafminers, with residual activity up to 30 d. It is fairly slow acting, with
effects seen 3-5 d after application; it is safe for many plants including blooms, but cannot be
applied to foliage or blooms of poinsettias. A label expansion allowing use on terrestrial-grown
ornamentals is pending, with EPA registration expected in 2006. Its selectivity for many
beneficial species and 12 h REI make it a good choice for use in IPM, but resistance
management considerations limit the number of applications in a growing season.
Other new products in the registration pipeline include several with as-yet unknown
modes of action. These include Overture (Valent), which shows excellent activity against
western flower thrips and various caterpillars. Targeted label use in greenhouse, nursery and
interiorscapes, it has translaminar activity, and a proposed 12 h REI due to its reduced risk status.
Aria (FMC) is in a new chemical class, with systemic and translaminar movement; no cross
resistance with neonicotinoids. It controls piercing-sucking insects, causing them to withdraw
their stylets, but they are not re-inserted; insects die due to starvation or dehydration, so it may
take 2-3 days before effects are evident. Older products have also been re-packaged; Whitmire
now market a Tame/Orthene combination in a total release formulation. This has provided very
good control of whiteflies, thrips, fungus gnats and shorefly adults, with mixed results against
aphids. Unlike a conventional liquid tank mix of these two products, the new formulation has
shown no phytotoxicity, even on blooms or poinsettia bracts in color. It has a 24 h REI.
New information and label changes. Distance has been around for a while, for use on
greenhouse and outdoor ornamentals, but there is always new information on use practices and
compatibility. When using as a spray, do not apply to poinsettias after coloring; when using as a
drench for fungus gnats or shore flies, do not drench heavily, apply to treat the upper layer of the
potting media only. It has now been tested against several beneficial insects and mites, with no
hazardous effects on parsitoids and predators. The Pylon label has been expanded beyond mites,
to include foliar nematodes, caterpillars and fungus gnat larvae; greenhouse tomatoes have been
added to the crop list, and the product is now available in 1 pint and 8 oz bottles. There will also
be some label changes for DySyston (furidan); commercial use of the 50% granular product on
outdoor ornamentals will be eliminated next year; as of 2005, this product can only be used on
Christmas trees. The 1-2% product will still be available for homeowner use.
On the mite front, TetraSan (Valent) is the hot new product, registered for use on
ornamentals in greenhouses, shade houses (interiorscape and outdoor nurseries on new label) in
all Northeastern states except NY. It has a different mode of action to other miticides such as
Akari, Floramite, Ovation, etc., so it is an excellent material to use in a spray rotation. It has
translaminar activity which means that good mite control can be obtained even when spray
coverage is a problem, and is effective against two-spot and several other spider mites, giving up
to 5 weeks of control. It is a mite growth regulator, but also has transovarial activity, so that
adult females will lay non-viable eggs. Because of its mode of action, it takes around 7 d for
observable effects, but is ultimately very effective. With a 12 h REI, it has good plant safety
(except for poinsettia bracts), and is safe for most beneficial insects. Packaged in water-soluble
bags, sprays are best made when mite populations are still low; if they are already high, consider
tank mixing with oil or soap to knock down adults. Resistance management: sprays must be at
least 14 d apart, with no more than 2 applications per crop, or 2 times per 6 mo, with at least one
other mode of action in between applications.
Three new miticides whose registration is pending: Shuttle (Arvesta) contains a new
active ingredient, so will be a useful resistance management tool. Granted reduced-risk status, it
has a 12 h REI and is registered for use on greenhouse and nursery crops e.g., for two-spot and
spruce spider mites. Studies in NY have not shown activity against cyclamen mite. It is largely
effective against mobile stages through contact, some activity via ingestion; no systemic activity.
Compatible with beneficial insects and predatory mites, some injury to rose flowers and tender
foliage has been noted at higher application rates. Judo (Olympic) is expected to be registered
by mid 2005; in a new chemical class – the tetronic acids – it controls a wide range of mites and
affects all stages, including eggs and adults. It also shows activity against whiteflies, and maybe
thrips. It has translaminar activity, and is safe for some beneficials. Ultiflora EC (Gowan Co.) is
undergoing registration for indoor and outdoor ornamentals; it has been assigned a reduced-risk
status by the EPA, so may be eligible for use on some edible crops. It is in the same chemical
class as Avid, but cross-resistance has not been observed. It is active against all life stages, and
in trials has been very effective against two-spotted spider mites.
Label changes: Floramite SC can now be used for mite control on greenhouse-grown
tomatoes larger than 1” at maturity, but growers must have a copy of the new label in their
possession at the time of application. Further, while still recommended as a resistance
prevention strategy, it is no longer required that Floramite be rotated with two applications of
products from alternative chemical classes, thus allowing the maximum two applications to be
made back-to-back. The manufacturer’s claim that the product is safe for predatory mites,
making it a useful product for bio-based IPM. A label expansion for Akari is expected soon, to
allow use on outdoor ornamentals, with broad mites and cyclamen mites being added to the
label.
Finally, disease management products. Updates on most developments have been
provided in previous sessions, so this will be a very brief foray into the plant disease world.
Somewhat old news, but BioWorks’ product MilStop was granted a 1 h REI in late 2003, and
was concurrently re-packaged in plastic buckets. It is also now OMRI approved. Recent trials
showed that the product provided excellent control of powdery and downy mildew. AgraQuest’s
Rhapsody (Bacillus subtilis) also gave fair to good control of these diseases in concurrent trials.
Again, a little on the old news side, Olympic introduced a new ornamental fungicide – OHP
6672 – for control of a broad range of diseases. The fungicide is available in two formulations,
and carries a 12 h REI. Another Olympic product, Sextant ornamental fungicide, is labeled for
several foliar diseases. Available as a flowable formulation, Sextant will be packaged in 4 x 1
gallon containers with a 12-hour REI. Sextant is from the dicarboximide family of fungicides
and appropriate resistant management practices should always be followed.
Two materials reported several years ago are currently receiving renewed attention for
use on ornamental crops. The first of these, Messenger, contains a harpin protein originally
isolated from the bacterium causing fire blight on fruit trees. The presence of the harpin protein
serves as a signal to the plant that a pathogen is present, stimulating the plant to activate its own
biochemical defenses; this can reduce disease development and new infections, a phenomenon
known as systemic acquired resistance (SAR). Based on the evidence of the SAR-inducing
activity of the harpin protein, Messenger is actively marketed for disease management.
Actiguard works in a similar fashion to activate a plant’s immune system and has primarily been
used for field-grown tomatoes. New trials on ornamentals should ascertain the utility of these
products for greenhouse crops, and provide growers with useful information on ways in which
these materials can be utilized. Watch this space.
Lastly, Crompton is actively developing the herbicide Mogeton for control of liverwort
and moss in containerized ornamentals. Efficacy and safety have proven to be superior to
products currently registered for the same purpose. Plans are to submit for EPA and federal
registration by the end of 2004. If approved, the company hopes to support growers interested in
pursuing Section 18 emergency exemption in individual states to allow further testing and use of
the product.
Disclaimer: This presentation was made at the invitation of the New England Greenhouse
Conference. Mention of a product or technique does not imply endorsement by the author.
Information contained in this article is provided in good faith on the basis of current information
acquired by the author from various source materials and individuals.
This article is accompanied by a PowerPoint presentation ‘What’s New’.