Vertebrate Pest Management for Grapes

Transcription

1 Vertebrate Pest Management for Grapes Roger A. Baldwin UCCE Wildlife Specialist-UC Davis

2 Species Identification (Ground Squirrels) Gray-brown fur with semibushy tail. Are social. Damage includes girdling of stems, consumption of fruit, gnawing of plastic irrigation pipes, and abundant burrow openings.

3 Species Identification (Ground Squirrels) Squirrels are active throughout the day and are frequently visible. They prefer to burrow on field edges and alongside fencerows and roadsides.

4 Species Identification (Pocket Gophers) Burrowing rodent about 6-8 in long; rarely seen above ground. Gopher mounds are plugged and often fanshaped.

5 Species Identification (Pocket Gophers) They feed on grape root systems and can girdle grapevines weakening and/or killing plants. Create numerous holes where irrigation water is lost. Mounds can also kill plants and can create weed seed-beds.

6 Species Identification (Meadow Voles) Have dark grayish brown fur and are 4-6 inches in length. Populations tend to cycle, exhibiting irruptive growth patterns.

7 Species Identification (Meadow Voles) Dig shallow burrows and leave well-worn trails. Primary damage caused by girdling of stems and gnawing of irrigation pipe.

8 Species Identification (Hares & Rabbits) Jackrabbits are hares, but they are the most common rabbit-like pest. Are larger and have longer ears than cottontails. Damage caused through foraging on stems and leaves of plants.

9 Species Identification (Hares & Rabbits) Cottontails are true rabbits. They are smaller and have shorter ears. They don t typically cause as much damage as jackrabbits but can be localized pests.

10 Species Identification (Deer) Can cause significant damage to grape plants, especially when fields are in close proximity to forested and riparian areas. Most damage will occur during dawn, dusk, and at night, so identification of footprints and scat may be needed to determine deer were the cause of damage.

11 Species Identification (Birds) Number of birds that will damage or consume grapes. These include robins, starlings, and house finches.

12 Current Control Strategies Currently, we focus on an integrated approach that utilizes a number of strategies and tools to control vertebrate pests.

13 Importance of Biology/Ecology Understanding the biology and ecology of vertebrate pests will guide management decisions. Example: - ground squirrels

14 What Control Options are Available? Habitat modification Baiting Burrow fumigation Trapping Exclusion Repellent Frightening Shooting Pocket gopher X X X X Ground squirrel X X X X X Meadow vole X X? X Hares & rabbits X X X X X X Deer X X? X Birds X X? X X

15 Control Options Biocontrol Natural predators have been used to control vertebrate pest populations. Falconers seem to work. Owl boxes are inconclusive at best. Gopher snakes kill a few pests but are unlikely to control populations.

16 Control Options Habitat Modification Involves altering habitat to reduce the desirability of pests to use vineyards. Examples: - eliminating preferred foods for pocket gophers reduces carrying capacity. - control vegetation within and around vineyards.

17 Control Options Exclusion Fencing, use of tree protectors, and netting vineyards is expensive and must be checked regularly to keep out vertebrate pests. However, exclusionary devices are sometimes the only effective strategy for minimizing damage from voles, rabbits, and deer.

18 Control Options Trapping Control of small populations of ground squirrels, gophers, and birds. Also effective at certain times of the year when other methods are less effective and can be a good follow up to alternative control methods. There are many different kinds of traps but all fall into 2 categories: - Kill traps - Live traps

19 Control Options Trapping Body-gripping traps, boxtype squeeze traps, snap traps, and pincer traps are common kill traps. Wire cage traps are common live traps. Live traps require euthanization of vertebrate pests.

20 Control Options Trapping Ground squirrels Trapping for ground squirrels is effective year round except during middle of summer. Conibear traps can be placed at burrow entrances.

21 Control Options Trapping Ground squirrels Gopher box traps can be used in tandem when set along runways. Live traps are also effective. However, they require euthanizing captured animals.

22 Control Options Trapping Pocket gophers Has many positive attributes including: knowledge that you ve removed the target animal. no use of toxic chemicals. available for use in organic setting. can be efficient and economical once user becomes proficient at trapping. Two main kinds of traps: pincers and squeeze-type box traps.

23 Control Options Trapping Pocket gophers - Exhibited high efficacy in wine grapes after two treatments. - Exhibited high efficacy in alfalfa after two treatments. Data slide removed. Data slide removed.

24 Control Options Trapping Traps such as this modified Australian crow trap can be used to capture certain resident species (e.g., starlings). Birds must be euthanized after capture. Not particularly cost effective for large numbers of birds.

25 Control Options Baiting Involves use of poison baits to control vertebrate pests. There are restricted use and non-restricted use baits. These vary depending on number of factors. Anticoagulants Zinc phosphide Strychnine Ground squirrels X X Pocket gophers X X X Voles X X Rabbits X

26 Control Options Baiting Anticoagulants - requires multiple feedings. - can be use for spot treatments, broadcast, or in bait stations.

27 Control Options Baiting Zinc phosphide - is an acute toxin. - potential bait shyness. - can be used for spot treatments and broadcast baiting. - not to be used in or around buildings.

28 Control Options Baiting Pocket gophers Strychnine works best. Use probe to find tunnel. Dispense bait in tunnel.

29 Control Options Fumigation Involves use of poison gas in burrows to control vertebrate pests. Works best when soil moisture is high (late winter early spring for gophers and after ground squirrels emerge in spring). Fumigants should not be used around buildings.

30 Control Options Fumigation Aluminum phosphide Tablets can be used for ground squirrels and gophers. Is a restricted use pesticide.

31 Control Options Fumigation Gas cartridges Only work on ground squirrels. Caution must be used with gas cartridges to prevent fires.

32 Control Options Fumigation Carbon monoxide producing machines

33 Control Options Fumigation Steve Orloff and I have already begun to collect efficacy data. PERC appears to be moderately effective, while the Cheetah was completely ineffective. Data slide removed.

34 Control Options Frightening Typically only effective on bird pests. Includes both visual and auditory devices. Common visual repellents include scare-eye balloons and mylar streamers.

35 Control Options Frightening Noisemakers include stationary devices (e.g., propane cannons, electronic distress calls) and devices shot by roving patrols (bird bombs, shell crackers). Stationary devices need to be moved every 5-7 days to maximize effectiveness.

36 Control Options Repellents Repellents rely on objectionable odors or unpleasant tastes. Can work for a short while, but effectiveness is spotty and usually only temporary.

37 Control Options Shooting Shooting can be effective in some situations, although it is labor intensive. Works best for ground squirrels and rabbits. Depredation permits can also be issued by local game wardens to take deer that are causing extensive damage.

38 Control Options Other Strategies Gas Explosive Device Involves combustion of propane and oxygen. Kills animal through concussive force and will destroy burrow system. May not be overly effective and has potential hazards.

39 Questions?