Introduction to Organic Brassica Production
By
Richard C. McDonald, Ph.D.
Symbiont
Biological Pest Management
Layout:
Tabs
(I, II, III, etc.) with headings/photos –
I. Introduction
to Organic Brassica Production - A. Organic Caveat. B. Organic Certification Costs/Agencies. C.
Start at the End. D. Why Broccoli? E. Taking Stock of Broccoli's Growth Habits.
II.
Organic Brassica Production
- A. Current System – schedule and planning; Enterprise budgets and necessary
equipment. B. Varieties. C. Soils/Rotation/Fertilizer/Lime/Water Requirements,
D. The Plant - seed, float trays, materials, transplanting, field plants (6
to 12 leaves), cupping plants (12-20 leaves), heading plants.
III.
Farmscaping/IPPM Concepts.
A. Introduction. B. Principles. C. IPPM vs. IPM. D. Top Farmscaping Plants.
IV. Insect
Pests and Natural Enemies A.
Introduction. B. Pests. 1. Imported Cabbageworm. 1.a. Cotesia glomerata. 1.b.
Pteromalus puparum. 2. Diamondback Moth. 2.a. Diadegma insulare.
V. Pesticides. A. Microbials 1. Bacillus
thuringiensis (Bt). 2. Impact of Bt on Natural Enemies. B. Soaps, and other
harsher controls.
VI.
Weed and Disease Control – no till production.
VII. Harvest/Post
Harvest Handling - when
to harvest? Harvest, cooling, boxing, storage, transport.
I.
Introduction to Organic Brassica Production
By
Richard C. McDonald, Ph.D., Symbiont Biological Pest Management, 194 Shulls
Hollar, Sugar Grove, NC 28679. phone/fax: 828-297-2884; email: the_edge@goboone.net; web:
www.drmcbug.com
A. Organic Caveat - All outcomes are based on
a complex set of systems - your management practices, weather, and other
factors may be different and have different results. What we are showing within has been demonstrated to work in both
scientific research/demonstration tests and direct field application over the
last 20 years. For the purposes of this
guide, most examples will be of broccoli.
B. Organic Certification - For a list of current
Organic Certification Agencies and costs, please contact the Carolina Farm
Stewardship Association at: www.carolinafarmstewards.org, e-mail
cfsa@carolinafarmstewards.org, or call (919) 542-2402.
C. Start at the
End, and Work Backwards
The
ultimate goal of this guide is to assist tobacco growers in producing a
bountiful, healthy crop of organic brassicas, especially broccoli. To ensure
the end product is up to the standards of a discriminating organic market, all
elements of the growing system must be in place and functioning from the moment
the seeds hit the ground. To identify what the essential elements of that
system are, let's start at the end of the process--with the product--and work
backwards.
D. Why
Broccoli?
Broccoli - brief history and description,
relation to other plants. Broccoli, Brassica oleracea var. italica Plenck, is a cruciferous
vegetable forming a short erect stem, which produces a large green head of
succulent flowers. Broccoli, cabbage and the other cultivars of Brassica
oleracea evolved from the colewort, a stout, weedy perennial of the seacoasts
of Great Britain and southwestern Europe. The present day broccoli was
developed by the Italians in the Middle Ages from bunched kale.
Currently, across the country this green, leafy cole crop is a hot
agricultural commodity. As food scientists, researchers, nutritionists, and
consumers alike have become aware of broccoli’s healthy food benefits, it has
been in high demand. That demand has created an excellent opportunity for
farmers. In addition, for those who have the experience and equipment for
growing tobacco, the growing system and equipment required to grow broccoli are
very similar: 1) Equipment currently used to produce
tobacco can also be used to start, transplant and cultivate broccoli; 2) The
season of broccoli (spring and fall) does not interfere with burley tobacco
production; 3) Broccoli is a high value
crop (for example, organic broccoli is consistently wholesaling for more than
$1.00/pound); and 4) Many farmers in this region are already acquainted with
growing cabbage as a cash crop, and thus the switch to broccoli would be easier
to make.
(PHOTO)
Caption:
This cruciferous plant of branching florets is the product that drives the
system that creates the market that makes farmers smile!
E. Taking Stock of Brassica
Growth Habits--The
key to producing a bountiful, healthy crop is learning the tricks behind each
crop. Take the broccoli example below:
If
you're considering growing organic broccoli or other brassicas, you'll be
pleased to know that by taking stock of the growth habits of the plant--and of
pest damage within the crop--you can increase your yield, and the presence of
beneficial insect populations. Here's how it works for broccoli (and
cauliflower):
1)
About 2/3rds of the way through a broccoli plant's life cycle, it begins to cup
or to attain a convex shape. At the cupping stage, plants typically have about
15 leaves. Cupping is the precursor to
the plant heading or bolting.
2)
Research has shown that, once broccoli plants have at least six leaves and up
to 15/16 leaves (just prior to cupping), they can withstand up to 50 percent
defoliation without a decrease in yield. In fact, moderate defoliation of the
plants--around 20 to 30 percent--actually increases yield.
3)
Defoliation causes certain plant chemicals to be emitted; these chemicals
beckon parasitic wasps and predatory insects to the plants.
4)
By allowing for a certain amount of defoliation, you encourage beneficial
insects to establish a foothold in the cropping system. They then begin
foraging in the area.
5)
As the plants cup, you want the fewest numbers of pests around and the most
beneficials. Cupping is the time to get particular about pest levels, and not
before.
6)
If pest levels at cupping time are above 2 caterpillars per plant, you can
spray a biopesticide, such as the microbial pesticide Bt (Bacillus thuringiensis - see Microbial pesticides below). This will
reduce pest numbers to an acceptable level with minimal harm to the
beneficials.
II. Organic Brassica
Production Guide Sheet.
Budget 2002-BR-1 Broccoli, Fresh Mkt,, Organic, Field Grown: Est. Revenue, Operating Exp., Feb. 02 Ann. Ownership Exp., & Net Rev./Acre/Crop.
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B. Varieties:
Broccoli:
Packman
(50 days) - least amount of pest pressure in studies at Virginia Tech. Blue
green color. ($240/# of seed). In
our experience, this is the early season workhorse; dependable – excellent
side shoot production. We’ve seen seedlings take 3 weeks of windy, 20-degree
weather and still perform. Head shape
tends to be more flat; in very wet years – can get bacterial soft rot (Low
pH can also cause this - see soil section for liming).
Arcadia
(62 days) – heat tolerant variety. Use
in summer months or in hot weather. Produces massive heads/huge plants. Heads are medium green and have a frosted
appearance. Big globular heads.
Supposed to work well with no-till.
Varieties Gypsy and Nomad are similar derivates of this cultivar that
work well in no-till and are resistant to soft rot.
Premium
Crop (62 days) - very tasty!
Beautiful, globular heads, decent side-shoot production. Dark green color.
($250/# of seed). Our favorite fall
crop. Resistant to soft rot.
Yield - should be close to 1-pound heads per plant, with a
six-inch stem below the head.
Cabbage:
Early
Flat Dutch/Flat Dutch –
Cauliflower: you may prefer
self-blanching varieties. Otherwise, the heads must be tied shut – use
different color rubber bands for different weeks.
Snow Crown
Kale:
C. Organic Brassica
Production - Soils, Lime, Fertilizer, Water Requirements and Crop Rotation:
Brassicas
grow best on well-drained, fertile soils that are rich in organic matter and
soil life. They dislike light, sandy, droughty soils, and very tight, compacted
or poorly drained soils. However, they can thrive in a fairly clayey soil
provided that the topsoil is biologically active and has good crumb structure.
Brassicas prefer a slightly acid to neutral soil, with a pH between 6.0 and
7.0, and liming is important if the pH falls below this range.
Although broccoli and related crops are not particularly deep-rooted, it is
important to be sure there is not a hardpan restricting root growth. Hard
pans often form at a depth of 6 to 12 inches as a result of repeated tillage
operations to the same depth. This reduces the accessibility of moisture and
possibly nutrients to the crop, and can restrict yield and cause apparent
"nutrient deficiencies" that are not corrected by fertilizer. If
a hard pan is present, it can be broken up by chisel plowing when the soil
is moderately dry. Follow chisel plowing with a deep rooted cover crop to
encourage biological activity deeper in the soil profile. This may significantly
enhance brassica yields, especially in dry years.
Broccoli, cauliflower and other brassicas are heavy feeders, and require plenty of available soil nitrogen (N), phosphorus (P) and potassium (K). They also need ample soil moisture, sufficient sunshine, and moderate soil temperatures (55 to 75 F) to sustain the rapid, steady growth that is essential to support good yields. Boron (B) is a critical micro-nutrient for brassica crops, and a B deficiency can cause "hollow stem" in broccoli or cabbage (interior of stem cracks and turns brown), and can lower marketable yields. Since soils in our region are often low in B, a boron supplement may be needed.
Recent research suggests that broccoli, cabbage and other brassicas prefer
a "bacteria-dominated" microbial community in the soil, and the
roots of many varieties secrete anti-fungal compounds to tip the balance in
favor of bacteria. This contributes to resistance to soil borne fungal diseases,
but it also inhibits the symbiotic mycorrhizae ("root fungi") that
help many other crops absorb moisture, and insoluble forms of P and micronitrients.
For this reason, sufficient amounts of readily available P and other nutrients
are needed for optimal growth in broccoli, cabbage and related crops. Rapidly-decomposable
organic materials (animal manures, young green vegetation, legume cover crops),
and finished compost made from a starting mixture that is rich in such materials,
will encourage a bacterial-dominated soil microbial community.
Soil Test
Several months before
planting broccoli or other brassicas, obtain a soil test through your Extension
office or a reputable private soil testing lab to evaluate your need for lime,
organic matter inputs and fertilizers. A&L Eastern Agricultural Laboratories
(7621 Whitepine Road, Richmond, VA 23237; tel. 804-743-9401), offers a standard
soil test (pH, organic matter, major nutrients) for $7.35, and a Boron test
for $3.50. To sample a field, take cores (surface to 6 inch depth) from at
least a dozen points evenly distributed through the field, mix thoroughly
in a clean plastic bucket or ceramic crock, and send a pint of soil to the
testing lab. You can use a soil corer (about $20, available through several
mail-order seed and farm supply companies) or a shovel and trowel to get the
samples. Dig out a shovelful, leaving a nearly-vertical surface, then use
the trowel to take an even slice from 0 to 6 inches from this surface.
Different soil labs use different methods and different units to report the
test results; however they will consistently indicate whether each nutrient
is present in low (deficient), medium (may be yield limiting), high (optimum),
or very high (ample, possibly excessive) quantities. If the pH is below 6.0,
apply lime at rates recommended by the lab. NOTE: when you lime, you are also
adjusting the balance of calcium (Ca) and magnesium (Mg) in the soil. Both
are essential elements for brassicas and other crops. If Mg is "low"
or "medium" on the soil test, use dolomitic limestone (widely available).
However, if Mg is "high" or "very high", and Ca is "low"
or "medium", use a calcitic or high calcium limestone. You can obtain
high-Ca lime through Seven Springs Farm (contact Ron Juftes at 540-6512-3228
or visit www.7springsfarm.com).
Your soil test will not directly tell you how much available N is present,
since levels of soluble N fluctuate widely through the season in both conventionally
and organically managed soils. However, the A&L test report includes an
"estimated nitrogen release" based on the percentage organic matter
(OM) and soil texture (sandy, loam, silty, clay). N is constantly released
by the biological decomposition of organic matter in the soil. If soil organic
matter levels are good (2% for a very sandy soil, 3-4% for a loam or silt
loam, and 4-6% for a clayey soil), the soil is well-drained and biologically
active, and it receives substantial annual organic inputs (compost, cover
crops, organic mulches, aged manure, etc), it can release 100 to 150 lb available
N per acre per growing season.
Fertilizer needs
Soil test recommendations
for broccoli and cauliflower may include as much as 150-200 lb/acre N, and
perhaps 100-110 lb/acre each of phosphate (P2O5) and potash (K2O) for a soil
that tests "medium" for these nutrients. Although these amounts
may be needed for a "tired" soil, or one in transition from conventional
to organic production, much less may be indicated for a fertile, biologically
active soil receiving a sufficient amount and diversity of organic inputs
(5 tons dry weight per acre per year). A biologically active soil will have
numerous earthworms (several to a dozen per shovelful), often shows fungal
networks and/or numerous small insect-like critters, and has a soft, crumbly
structure. It will show moderate to high OM levels on a soil test. Very sandy
soils may support few worms, but will become noticeably darker and better
aggregated (crumb structure) as biological activity increases.
On most soils, a starter organic fertilizer with an analysis of 5-4-5 or 5-5-3
(often based on composted poultry litter) should be used at time of planting
to supply up to 50 lb/a N (and corresponding amounts of P2O5 and K2O). This
will boost growth early in the season, when cool soil temperatures can retard
nutrient release from even the most fertile and biologically active soils.
If the soil is also low in boron (B), be sure to include a boron supplement
to supply 1-2 lb B per acre. Mix the B supplement thoroughly with the starter
fertilizer, and do not exceed 2 lb elemental B per acre, as this can be toxic
to other crops in your crop rotation. Boron can also be applied in transplant
water. If additional N is needed during crop growth, you can side-dress with
any of several organic N fertilizers, or use liquid fertilizers based on fish
and seaweed (applied as foliar spray or through drip irrigation).
If the soil tests low in P, K and organic matter, incorporate some nutrient
rich manure compost or aged manure prior to planting broccoli. Aim to supply
perhaps 100-150 lb P2O5 and 150-200 lb K2O. This can be achieved with applications
of 5 to 10 tons per acre of aged manure (depending on manure source - get
a nutrient test on the manure so you can fertilize more precisely). Remember
that, for organic certification, "raw" manure (which includes aged
manure that has not gone through a rigorous composting process) must be applied
at least 120 days before first harvest - so either get it on early, or compost
it thoroughly first.
If just P is low, another way to boost soil P level is to apply Rock Phosphate
or Colloidal Phosphate at 500 to 1000 lb/acre. This is somewhat expensive
but you will only have to do it once. Soil tests may show only a slight increase
in available P, but the element is there, and it will gradually become more
available to the crops if you enhance soil biology through cover crops and
high quality compost. If K is low but P is sufficient, remember that hay mulch
is a particularly rich source of K. Spread hay mulch at 5 to 10 tons per acre
once the broccoli is well established. The mulch also retains soil moisture,
suppresses weeds and feeds soil life.
Calcium (Ca), magnesium (Mg) and sulfur (S) are also important nutrients for
brassicas. Proper liming (see above) should take care of Ca and Mg needs.
Crop limiting S deficiencies are relatively rare, but if one is suspected,
you can get a test for S included in the soil test for a few extra dollars
per sample. S can be supplied with gypsum (calcium sulfate), sul-po-mag or
Epsom salts (magnesium sulfate). Use gypsum if Ca is low to medium, sul-po-mag
if Ca is ample and neither K nor Mg is "very high", and Epsom salt
if Mg is low relative to K and Ca.
Too much P and K can be a problem too!
Soils managed organically
for a number of years with heavy inputs of manure, compost and applied mulch
can accumulate very high or excessive P and K levels. Soil test labs often
recommend some P and K even when test levels are high to very high, but this
may be unnecessary on organically managed, biologically active soils. In fact,
continuing to apply these nutrients, either as organic or mineral amendments,
can upset nutrient balance and harm crop yield or quality.
Another common situation during transition from conventional to organic methods,
is a soil that is depleted of organic matter (less than 2.5 percent on medium
textured Appalachian soils) but very high in P and K. This results from intensive
applications of chemical NPK fertilizers - all the N gets used up and/or leached
out, but the P and K accumulate.
Growing legume cover crops is the best way to replenish and maintain N and
OM levels in soils that already have ample or excessive P and K. Other than
a light application of starter fertilizer to get the brassica crop off to
a good start, manure-based composts and organic fertilizers and hay mulch
should be avoided, as they will aggravate the nutrient imbalance. Plant a
mixture of hairy vetch and winter rye, or for early spring brassicas plant
a non-hardy cover crop mix such as oats + lana vetch or berseem clover, or
millet + soybean or cowpea. For the OM-rich soil that has built up too much
P and K, the cover crop may be sufficient. For the tired "dead"
soil that got its P and K overload from conventional fertilizers, use a high
quality compost (1-3 tons/acre), vermi-compost (worm castings), biodynamic
preparations, and/or other soil microbial inoculants to introduce a diversity
of beneficial soil organisms. These are just as important as NPK and B for
success with brassicas. If the crop appears hungry for NPK, foliar feed with
a fish fertilizer at recommended rates. You will get a significant response
and it won't overload the soil with these nutrients.
Irrigation
This may be the last thing on your mind after the Great Monsoon of 2002-03, but remember that brassicas are not all that deep rooted, and may require irrigation during warm dry spells. These crops generally need about one inch of water per week, and require irrigation if rains do not provide this moisture. Drip irrigation is strongly recommended for delivering moisture and nutrients directly to the crop row. If you do not have a drip setup, overhead sprinkler irrigation is much better than none at all during a drought. An organic mulch of hay, or an in-situ rolled-down cover crop mulch can help conserve soil moisture, reducing irrigation needs, and potentially saving a crop for farmers that do not have access to irrigation.
Crop rotation
Since brassica crops
are subject to a number of insect pests and fungal diseases, a sound crop
rotation is important. Crops in the crucifer (brassica) family should be planted
only once every four years (minimum 3 years) in a given bed or plot. This
plant family includes cabbage, broccoli, cauliflower, collards, kale, kohlrabi,
radish, turnip, rutabaga, arugula, mustards, bok choy, Chinese cabbage, and
several other specialty Oriental greens. Brassicas can be rotated with beans
and other legume vegetables, tomatoes, potatoes, corn, squash family, lettuce,
onion family, carrots, beets or spinach. Include cover crops within the rotation
scheme to rest and rebuild the soil, and encourage beneficial insects. Brassicas
thrive particularly well after legume cover crops, and/or onion-family (garlic,
leeks, onions, scallions), all of which have subtle beneficial effects on
the soil. The legumes also provide extra N, on which the brassicas thrive.
Crop rotation is an essential component of pest control for cabbage root maggot,
flea beetle, and possibly caterpillar pests. Rotation breaks up the life cycle
of flea beetle and root maggot, both of which have a key part of their life
cycle in the soil. If these are serious pests, plant next year's brassicas
at some distance from this year's crop, rather than in an adjacent bed or
plot, into which pest larvae may migrate.
Clubroot is a particularly stubborn fungal disease of brassicas. A four-year
rotation is a good preventative, but if clubroot appears in a field, you will
need to exclude brassicas from that field for at least seven years. Keeping
soil pH at about 7.0 also deters clubroot fungi. Fortunately, clubroot does
not appear to be very common in our region - but some vigilance and good rotation
may be needed to keep it that way!
Water needs: Broccoli needs roughly one inch of water per week.
D. The Plant – Broccoli featured here.
Photos with captions:
Seeds/starts
– plant in 288 cell “Speedling” flats (200 cell flats would work well, too) in
a raised float bed in heated greenhouse.
Transplants
- These plants were scouted and cared for until they reach the 6-leaf stage
(8 to 10 weeks old) in one inch Speedling flats; 4 to 5 weeks in three quarter
inch Speedling flats. Plants are then
hardened off outside for a week or so prior to planting.
Direct
set in the field with12-16 inch centers on 30-inch rows.
Field plants (6 to 12 leaves) – this is when you can tolerate some damage in order to get beneficials established. Scout at least 20 plants/acre in an X pattern in the field and release beneficials if necessary. This ensured a favorable beneficial to pest ratio of 25% to 33% of scouted plants with beneficials present (see Table 1).
Cupping
plants (12-20 leaves) – Usually 10 to 14 days out before harvest; depends upon
temperatures. Time to make sure plants are clean of pests just prior to
harvest. Use Bt variety kurstaki for
most caterpillars. You will need to rotate Bt varieties and other microbials
(CLV) – viruses; otherwise you’ll get resistance.
Heading
plants – watch closely for signs of insects.
Cut heads open to check for cabbage aphids and other insects. If lots of
rain, harvest early to avoid brown spot and other wet rots.
III. IPPM and Farmscaping. A Banquet
Held in Honor of Your Favorite Beneficial Insects or “Build It, and They Will
Come”.
A. Introduction
Bearing in mind that the growing
system for brassicas starts with a field of healthy, fertile soil, the next
most crucial element of the system is the incorporation of an effective pest
management strategy. By planting specific beneficial plants, you will create an
environment that entices the good insects to be there when you need them to
battle the bad insects. Research has shown that incorporating specific plants
into the borders and some pullout rows of your broccoli will ensure the
continuous presence of beneficial insects in your field throughout the growing
season. By working backwards to
identify the types of insect pests that typically attack crucifers in this region,
you can fortify your field with adequate numbers and varieties of natural
enemies. When the pests do arrive, your beneficial insects will meet them at
the gates. In order to keep these good bugs around, you need to have AT LEAST 5
percent of your broccoli field planted with beneficial farmscaping plants. This
doesn’t have to be IN the field; it can be right next to it, if you have
ditches, banks or other areas you can plant. My motto regarding the
incorporation of beneficial insects into the field is: If I lay a banquet for them, they will come.
B. Principles of Organic
Brassica Integrated Parasite and Predator Management (IPPM).
First, start at the end and work backwards,
as we said before-
The ultimate goal of this guide sheet
is to be able to help you produce a bountiful, healthy crop of organic
brassicas (focusing on broccoli as our example) and at the same time, build an
organic system of beneficial border plants and beneficial insects into your
field to ensure that you will get a healthy productive broccoli crop every
time.
So, the first thing (after making sure
your soil is fertile and healthy) you want to do is begin to have areas along
and in your field that your beneficial insects can live and reproduce in. You need to have around 5% of your broccoli
field planted with beneficial farmscaping plants in order to keep the good
bugs around. Farmscaping: So, the area to be planted - i.e. for an acre at
5%: 43,560 sq.ft = 2200 sq. ft. of farmscaping plants). More small plots spread out is better than one big plot. Second,
some interesting facts about broccoli that will come in handy.
PHOTO: Broccoli plant at the cupping
stage.
You can take advantage of the growth
habits of broccoli to increase your yield and your beneficial insect
populations. Researchers learned that
broccoli plants could withstand up to 50% defoliation without a decrease in
yield. In fact, moderate defoliation
(around 20 to 30%) actually increased yield!
So by being able to allow for a certain amount of defoliation, you can
help your biological control prospects.
Your natural enemies will have 'food' and other requisites in order to
stay where you want them.
A broccoli plant will grow to a
certain point and then 'cup'. This
cupping occurs about 2/3rds of the way through the plant's life cycle, and is
the precursor to the plant 'heading'.
Once the plant begins to head, it is extremely important to keep pests
out of the head area.
So, we can closely monitor the growth stages of a broccoli plant. We know that we can tolerate some
defoliation before the plant cups in order to make sure our beneficials are
established and working. We also know
that defoliation will not hurt, and in most cases, actually help yield.
As the plant begins to cup we know that we want the fewest amount
of pests around and the most amount of beneficials as the broccoli heads begin
to mature. This is the time to get
particular about pest levels, and not before!
If pest levels at cupping time are above your economic threshold, then
you can consider spraying a specific biopesticide (like the microbial pesticide
Bt (Bacillus thuringiensis) that will
reduce pest numbers to an acceptable level with minimal harm to the
beneficials. Otherwise, by wisely
planning ahead and using some farmscaping principles to encourage beneficial
insects, you will have a healthy population of beneficial insects, such as
ladybugs, parasitic wasps, predatory beetles, bugs and flies that can suppress
pest populations all season long.
C. IPPM vs.
IPM.
Imagine you've just received an
invitation in the mail to attend a banquet being held in your honor. The menu
accompanying the invitation lists all your favorite foods. Are you going to come? You bet you are!!
The gist of this analogy is that just
like us, beneficial insects need sources of food and shelter in order to stick around. You can weave 'web of life' in
your field by planting specific plants. Also, by thinking ahead and
anticipating the types of pest problems you might have, you can encourage the
right beneficial insects to be there when you need them to attack the
pests. My motto is: If you plant it,
they will come. Or, I will buy them (beneficials) once and have them here
forever after...'
In keeping with this perspective,
think of two terms: 1) Farmscaping, which is the deliberate planting or
modification of an agricultural environment with specific plants to encourage
populations of beneficial insects. 2)
IPPM - Rather than the term IPM
(Integrated PEST Management), I encourage you to be thinking IPPM - Integrated
PARASITE and PREDATOR Management (This term comes from Dr. Everett Dietrich,
the grandfather of beneficial insect rearing).
These two comparisons are equal to the difference between Eastern and Western medical thought--Western medicine treats the illness or its symptoms, while Eastern medicine, with its use of tonics, focuses on keeping you well in the first place. It is the same with your garden or farm. By using IPPM and having the beneficials there IN THE FIRST PLACE, you can nip many of your pest problems in the bud before they ever have a chance to become a problem. So let's look at a few ecological principals to make your broccoli field more attractive to beneficial insects:
Ţ ***My IPPM GOAL-you want 1/4 to 1/3 of the “target” plants you
sample to have some indication of beneficial insect activity***(wasps, cocoons, mummies,
partially eaten egg masses, etc.) or to be relatively pest free. Remember the
goal is a “balance” tipped in our favor. Sample at least weekly or more often
if a pest problem is present – if possible, sample about 1/4 to 1/3 of the
plants (if you want to run statistics on your data). Farmscaping – Dr.
Robert BUGG - Definition: Deliberate use of specific plants and landscaping
techniques to attract and conserve “Beneficials”.
Feed your bugs – Dr. McDonald’s Baker’s
Dozen: Applied Farmscaping Principles:
Ţ 1) Farmscaping is part of a Multiple Redundant Systems (MRS) approach – MRS is a form of disaster preparedness – triple redundancy is desirable for plants and insects. So for both you want “guilds” of food plants and natural enemies to protect your plants. This is why we list more than 10 beneficial food plants per season – more than one natural enemy attacking each life stage is better, too. Less can lead to breakdowns. You Want A Natural Enemy for Each Life Stage of the Pest(s). Let's take the Imported Cabbageworm Butterfly (ICW) as an example. It has life stages starting with egg, larva (five different instars), pupa, and adult. So it really has eight different stages that we need to have something attack. Our best chance of sustainable suppression is to make sure we have a complex of natural enemies for each specific life stage. There are ladybugs, Trichogramma wasps, and other predators that can attack the egg stage of the ICW. Likewise, ladybugs will gladly consume ICW caterpillars and there are several specific wasp parasites that sting and lay eggs in ICW caterpillars, especially the first three instars. For the pupal stage, we know that the parasitic wasp