**1. Introduction**

In the tropics, the diversity of plant species is very high, although the species richness is not so great because they share the habitat with the other biological forms of that environment, such as shrubs, vines, lianas, parasitic epiphytes and palms.

In Mexico, for a long time precious woods such as cedar (*Cedrela odorala* L.), mahogany (*Swietenia macrophylla* King.), spring (*Cybistab Donnell-Smith*) and red (*Haematoxylum campechianum* L.) were exploited to take them to other continents for various cabinetry work, to the extent that the ecosystems of the Mexican tropics were impoverished by an extraction of eugenic type, that is, taking advantage of the best quality trees with straight stems and larger diameters.

This extraction in some cases has caused the disappearance of habitats due to extractive recurrence, thus favoring that the trees do not reach their physiological maturity, although their reproductive maturity does.

On the other hand, the establishment of exotic forest plantations such as teak (*Tectona grandis* L.f.), rubber (*Hevea brasiliensis* [Willd. ex A. Juss.] Müll. Arg.), melina (*Gmelina arborea* Roxb), pine (*Pinus caribaea* Var. Hondurensis [Sénécl] W.H.G.) or eucalyptus (*Eucalyptus* sp), Oil palm (*Elaeis guineensis* Jacq.) by large corporations, has caused the reduction of the surface of the original vegetation,

because when establishing these plantations all the vegetation present is eliminate, and far from supporting the local population, it exterminates the environments of the area, leaving only pockets of impoverished land to restore part of the lost biological diversity.

In this sense, forest nurseries of local species are created in order to provide seedlings to recover the strongholds of impoverished areas, potential environments or even include other environments for conservation.

For this purpose, the availability of germplasm is an activity of transcendental importance in which the possible progenitors are located, the period of flowering and fruiting is expected and later the seed is collected. This seed is taken to the nursery, processed, sown and the emergence of the seedlings is expected. At this stage, the management and care of the seedlings is of utmost importance because they are more susceptible to attack by pests and/or disease of any pest or illness.

Under this concept, in order to generate information about the main pests of some forest species used in reforestation in a mixed way, ten germination and growth beds of various local forest species were established. It is possible that due to the difference in habitat conditions between the site where they grow naturally and the nursery conditions where they were produced, some pests and diseases were present both in germination beds and growth beds and that are reported in this work.

Currently, it is a common practice to produce forest plants in a nursery and when the seed does not come from certified seed banks, these generally already bring the pest from the harvest field in a certain percentage, which are not suitable for cultivation.

When the percentage of impurities has been eliminated, the resulting seed is sown in bags, tubes, trays or germination beds depending on the size of the seed and wait for them to germinate. During the process of germination and growth of seedlings some diseases occur.

## **1.1 Damping off** *Rizotocnia*

This is a type of opportunistic fungus that occurs when excess moisture in the site is above what the plant can dispose of. This excess moisture ends up rotting the stem of the seedling. They generally call it a dryer and it is common in various species of plants in the region such as cocoite, cedar, bojon, guanacaste, to name a few species and generally what is presented is the mycelium since they rarely form structures of sexual reproduction.

This fungus is very damaging as it forms resistant structures called interconnected Sclerotia that infect the roots of newly emerging plants and can rapidly spread over much of the germination bed.

Its presence is greater in alkaline soils with poor drainage, so generally the substrate must be fumigated with methyl bromide before sowing, covered with plastic and uncovered after two days so that there is aeration, and the seed is sown after 72 hours of aeration.

Another very common fungus is Fusarium sp., and it occurs when the seed generally does not go through an antifungal treatment before sowing, so the fungus Fusarium oxysporum attacks the external and even internal structures of the seeds. The newly emerged seedlings are covered with a white mycelium that affects the new organs of the plant, which is controlled using thiabenzadol at a dose of 1 g per l of water.
