NURSERY CERTIFICATION

The terminology associated with government run programs for managing nematodes on nursery stock is complex and confusing to those not directly involved. Terms such as sanitation, quarantine, control, and certification have specific legal meanings which are not intuitively obvious and are easily misused as they may be in the ensuing discussion. California has both external programs dealing with plants imported into the state and an internal nursery nematode control program dealing with fruit and nut trees, grapevine, berry and vegetable plant nursery stock grown within the state and destined for commercial farm planting. Plants grown within the state for other than farm planting are not protected by the internal programs.

Historically, the nursery nematode control program for planting stock destined for commercial farm planting was mandatory and publicly funded. Recent budgetary problems threatened the elimination of the program. Currently the program is voluntary and funded by nursery assessments, although stock which is not part of the program cannot be sold within the state.

California's nursery nematode control programs were established based on recommendations of CDFA's Nematode Study Commitee composed of County Agricultural Commissioners, nursery owners, University of California nematologists and CDFA personnel. In recent years, meetings of this committee have been infrequent.

An important point that is not always obvious is that the more successful a quarantine or nursery control program is, the greater jeopardy the program may be in. A successful and well run quarantine program will result in greater precautions on the part of those shipping plants into the state because of the financial losses that will occur if infested plants are found. Internally, a well run nursery program will, over a period of time, result in greater precautions on the part of nurseries with a subsequent drop in the number of infestations discovered. Nematode sampling and processing is time consuming and therefore expensive. Because of this, when budgets are tight, government personnel may naively and erroneously assume that a program with only a few positive findings each year is no longer necessary.

In reality, California's extremely successful internal and external sanitation programs have probably resulted in keeping several potentially devastating nematodes out of the state and others confined to relatively few acres within the state. Any slackening of vigilence can relatively quickly result in the infestation of new areas. For example, one acre of infested nursery stock can result in the infestation of more than 100 acres of farm land. Successful attempts to erradicate nematodes are rare, or perhaps even nonexistent.

RADOPHOLUS SIMILIS:

56 INTERCEPTIONS 1988-1994 For many years, California has had a mandatory quarantine for burrowing nematode. Although there has been no program for reniform nematode which argueably would be as much if not more damaging to California agriculture, this nematode has often been intercepted in samples being examined for burrowing nematode. Data for this list were compiled by CDFA and illustrate the wide range of crops on which R. similis has been found on plants imported into California.

It is interesting to note that although the main concern from this nematode is for farm planting, the potential for importation on ornamentals is a major problem.

ROTYLENCHULUS RENIFORMIS:

40 INTERCEPTIONS 1988-1994

Data for this list were compiled by CDFA and illustrate the wide range of crops on which R. reniformis has been found on plants imported into California. The symptoms on pineapple (stunted roots in center of picture) illustrate the potential seriousness of this nematode for California agriculture

These findings were as a result of examinations for burrowing nematode because California did not have an official quarantine on R. reniformis.

It is interesting to note that although the main concern from this nematode is for farm planting, the potential for importation on ornamentals is a major problem.

COST OF PRODUCING FRUIT AND NUT TREE ROOTSTOCKS:

For many years, California has had a strong nematode nursery control program for planting stock destined for commercial planting.

As a result of recent state budgetary problems, the funding for this program has recently switched from public to private sources.

Because of the upfront costs involved, nursery programs are often viewed as very costly.

However, if one considers how this cost breaks down for an acre of planting stock as illustrated by this example, the costs are actually rather minimal. The plant spacing figures and harvest estimates were provided by a commercial California nursery.

STRAWBERRY CERTIFICATION:

A certification program for strawberry nursery stock has been in place in California for many years to assure fruit production planting stock is free of nematodes. Foliar nematode (Aphelenchoides fragariae) and root-knot nematode (particularly Meloidogyne hapla) have been the nematodes of most concern in California. Plants from nursery fields (photo) are sampled on a 40 x 40 foot grid (conveniently using sprinkler pipes for spacing). If infested plants are found, the area of infestation is delimited by additional sampling. This graph prepared from California Department of Food and Agriculture (CDFA) records demonstrates how an effective nursery inspection program can improve the cleanliness of nursery stock. When the nursery program was first initiated, infestations of foliar nematode were relatively common. Recently, in some years, no infestations have been found. Unfortunately, this situation has led some officials to feel the program is no longer needed. Economically, in a state suffering severe budget problems, it is hard to justify using public funds to support a program which appears to yield only negative results. Fortunately, after much discussion, funding for the program has been changed from public to private sources.

In contrast to strawberry fruit production fields which are maintained in well defined rows,strawberry nursery fields at the time of harvest are a mass of entertwined foliage. Symptoms of foliar nematode on strawberries are not well defined and not easy to spot in a nursery production field. In this photo, a healthy plant is on the left and a plant infested with A. fragariae is on the right. In addition to stunting, note the differences in fruiting and flowering between the two plants.

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