Changing
Agricultural Practices Through Integrated Pest Management - IPM: Examples From
Fruit Production
Dean Polk, Statewide Fruit IPM Agent
Rutgers Fruit Research and Extension Center
283 Rt 539, Cream Ridge, NJ 08514
(609) 758-7311, fax: 758-7085
From Where We Evolved - Life
With No IPM
Fruits
are perennial crops grown in permanent or semi-permanent systems. Apples can be
exposed to over 37 different arthropods and 20 diseases. Peaches and small
fruit like blueberries must be managed for the presence of more than 2 dozen
arthropods and a similar number of diseases. Given this pest pressure,
pesticides and pest management have been historical parts of fruit production.
Pests are classified as either direct or indirect pests. Indirect pests are
those pests that cause injury primarily to the plant, devitalizing the plant
leading to secondary damage in the form of reduced crop size, yield or quality.
Direct pests are those pests that feed and injure the fruit directly, such as
the ‘worm in the fruit’. In many cases direct damage is only cosmetic, but
because cosmetic value is important in fruit marketing, surface blemishes and
irregularities cannot be tolerated.
The
middle part of this century saw a revolution in the development of new
pesticides. The materials were economical to use, and solved pest problems
quickly and easily. With the use of modern pesticides, calendar based spraying
became standard practice during the 1940s through the 1970s. It was (an
sometimes still is) common for fruit growers to apply tank mixes of several
fungicides and insecticides at regular intervals throughout the season. With a
good sprayer it became relatively easy to keep a constant cover of plant
protectants applied to both plants and fruit. Given growers' time and risk
considerations, it is relatively easy to reduce pest injury risks by practicing
a calendar based spray method, routinely applying predetermined pesticides at
one week to ten day intervals. Pest monitoring, threshold levels, biological
controls, or other pest management technologies were not part of the picture.
However, intensive pesticide use led to the development of resistant pests. It
killed parasites and predators, helping other arthropods develop into secondary
pests. With more pests, pesticide use increased. Recent developments such as
increased pesticide costs, development of resistant pest strains, regulatory
pressures, and new technologies have encouraged more farmers to adopt IPM/ICM
strategies. Under standard practices, fruit may be sprayed up to 12 times or
more throughout the growing season, and exceed $500 to $600 per acre for high
value fruit.
IPM - What Is It?
IPM
is simply the use of all available techniques to manage pests below
economically damaging levels while maintaining or increasing crop quality and
yield, including the use of monitoring, record keeping, use of action
thresholds, cultural, biological, and host plant resistance practices. Early or
First Stage IPM was based on monitoring pest populations and treating with
pesticides based on proper timing and treatment threshold levels. While these
practices led to reduced pesticide use, the system was still pesticide based,
and reductions were limited. Second stage IPM, as defined by Prokopy in
Massachusetts, is more biologically based. It includes pesticide replacement
strategies, like the use of red sticky balls to trap out apple maggot flies to
prevent entry into an orchard. Later or third stage IPM can be more biologically
based. For example, over 50% of the pesticides used in eastern apple production
are for disease control. Three quarters of this is for early season control of
apple scab, powdery mildew, cedar apple rust and fire blight. The use of
disease resistant cultivars (DRCs) can eliminate most pesticides used for those
diseases. Integrating resistant varieties with trap out methods and other
biologically based alternatives increases the impact of those IPM practices.
The newest and most ‘integrated’ IPM programs include the management of all
pests - plant pathogens, nematodes, weeds, arthropods, mammals, and birds.
Since this entails an ecological systems approach, agronomic or horticultural
practices must also be considered. Therefore, the term integrated crop management
(ICM), has often been used interchangeably with IPM. Some workers refer to
these as integrated crop and pest management (ICPM) practices.
The
following stages outline how IPM has evolved in NJ fruit production for the
past 22 years.
Stage
1: Started in the early ‘80s, apple growers formed the basis of NJ fruit IPM
programming. Realizing the complexities of pest management, and the increasing
costs of ag. chemicals, growers contributed funding to a ‘First Stage’ IPM
program, based on scouting and the use of action thresholds and native
biological controls. The average grower reduced pesticide use (compared to
previous years and non-IPM growers) by about 18-20%, with use in successive
years being maintained at similar levels.
Stage
2: Fertility management was folded into the program in the mid ‘80s with soil
and leaf tissue monitoring, as was testing for plant parasitic nematodes.
Growers traditionally used balanced 10-10-10 or 15-15-15 fertilizers even on
soils with high phosphate levels. Soil pH was often not optimal, often leading
to high use rates of plant nutrients. A number of growers reduced phosphate
use, and optimized their fertility program.
Stage
3: Integrating the use of disease resistant apple cultivars: Starting in 1988,
an 8 year SARE funded program for apples established plantings and demonstrated
IPM practices that reduced total pesticide use by 60 to 70%. While this led to
several plantings on organic and traditional farms, consumer education and
marketing issues restrict wider adoption of the technology.
Stage
4: Computer-based pest phenology modeling: Modeling can refine the timing and
optimize the control for insects and diseases. Simple degree-day models may use
only a max-min thermometer set in an orchard. Disease conditions may be
predicted based on temperature, humidity, and the length of wetting periods.
Today growers have access to an automated system, via fax or e-mail, based on
NOAA satellite, balloon and ground data, which is combined with the proper
algorithms for pest prediction. The technology has improved pest control, and
in the case of oriental fruit moth, reduced insecticide use in peaches by 40%.
Stage
5: Use of mating disruption – New pheromone delivery methods have made it
possible to control certain pests with the mass placement of insect sex
pheromone, preventing or delaying mating and successful reproduction. Use of
this technology in peaches has resulted in up to 60+% reductions in insecticide
use. Savings are fully realized when mating disruption is combined with the
cultural practice of maintaining clean ground covers.
Stage
6: Use of an IPM database - grower education and demonstration through the use
of their own data: Starting in 1997, an IPM database, IPMD was developed as a
teaching and research tool. It is used to track fertility and nematode levels,
pesticide use, fruit quality, and the impact of specific grower practices. Some
growers have requested adaptations of the database, and will be using it on
their farms in 2002.
Stage
7: Use of Geographic Information Systems (GIS) in IPM programming: Accurate
acreage figures for individual plantings can be used to properly calibrate
sprayers. Area/State-wide pest maps can help predict pest populations and
identify ‘hot spots’ in various areas. On individual farms, spatially specific
data can identify locations of pest activity, permitting treatment only in
those areas. Maps can also be used to identify soil types, thus adjusting herbicide
rates, map crop yield, and may be used for farm labor, field scouting and
insurance purposes. All Fruit IPM participants are provided with geo-referenced
base maps that can be used for these purposes.
Stage
8: Stimulating additional grower adoption through public education: Existing
programs and adoption are limited by existing technology and possibly by a
limited public understanding about IPM. While new technology continues to
provide new materials and tools, the lack of public understanding also seems to
limit what some growers can practice. Consumer interviews have suggested a
favorable response to produce identified as IPM grown. Growers interested in
consumer education are using posters and other materials in their own consumer
education efforts.
Growers
now have a menu of IPM practices from which to choose. Further adoption will depend in part on
production costs, available technologies and materials, and marketing
influences.